tTNIVEBSITY OF CALIFOBNIA PUBLICATIONS 
 
 COLLEGE OF AGRICULTURE 
 
 AGRICULTURAL EXPERIMENT STATION 
 
 BERKELEY, CALIFORNIA 
 
 I. FUMIGATION WITH LIQUID 
 HYDROCYANIC ACID 
 
 BY 
 H. J. QUAYLE 
 
 II. PHYSICAL AND CHEMICAL 
 
 PROPERTIES OF LIQUID 
 
 HYDROCYANIC ACID 
 
 BY 
 GEO. P. GRAY AND E. R. HULBIRT 
 
 BULLETIN No. 308 
 
 JUxVE, 1919 
 
 UNIVERSITY OF CALIFORNIA PRESS 
 
 BERKELEY 
 
 1919 
 
Benjamin Ide Wheeler, President of the University. 
 
 EXPEEIMENT STATION STAFF 
 
 HEADS OF DIVISIONS 
 
 Thomas Forsyth Hunt, Director. 
 Edward J. Wickson, Horticulture (Emeritus). 
 
 Herbert J. Webber, Director Citrus Experiment Station; Plant Breeding. 
 Hubert E. Van Norman, Vice-Director; Dairy Management. 
 William A. Setchell, Botany. 
 Myer E. Jaffa, Nutrition. 
 Charles W. Woodworth, Entomology. 
 Ealph E. Smith, Plant Pathology. 
 J. Eliot Coit, Citriculture. 
 John W. Gilmore, Agronomy. 
 Charles F. Shaw, Soil Technology. 
 
 John W. Gregg, Landscape Gardening and Floriculture. 
 Frederic T. Bioletti, Viticulture and Enology. 
 Warren T. Clarke, Agricultural Extension. 
 John S. Burd, Agricultural Chemistry. 
 Charles B. Lipman, Soil Chemistry and Bacteriology. 
 Clarence M. Haring, Veterinary Science and Bacteriology. 
 Ernest B. Babcock, Genetics. 
 Gordon H. True, Animal Husbandry. 
 James T. Barrett, Plant Pathology. 
 Fritz W. Woll, Animal Nutrition. 
 Walter Mulford, Forestry. 
 W. P. Kelley, Agricultural Chemistry. 
 H. J. Quayle, Entomology. 
 J. B. Davidson, Agricultural Engineering. 
 Elwood Mead, Eural Institutions. 
 H. S. Eeed, Plant Physiology. 
 J. C. Whitten, Pomology. 
 IFrank Adams, Irrigation Investigations. 
 C. L. Eoadhouse, Dairy Industry. 
 Frederick L. Griffin, Agricultural Education. 
 John E. Dougherty, Poultry Husbandry. 
 S. S. Eogers, Olericulture. 
 J. G. MooDEY, Assistant to the Director. 
 Mrs. D. L. Bunnell, Librarian. 
 
 DIVISION OF ENTOMOLOGY 
 
 Citrus Experiment Station at Eiverside 
 
 H. J. Quayle *A. F. Swain 
 
 Hugh Knight 
 
 Division of Entomology at Berkeley 
 
 C. W. Woodworth G. P. Gray 
 
 W. B. Herms S. B. Freeborn 
 
 E. C. Van Dyke G. A. Coleman 
 
 E. O. Essig H. H. Severin 
 
 E. E. DeOng 
 
 t In co-operation with office of Public Eoads and Eural Engineering, U. S. 
 Department of Agriculture. 
 
 * In war service. 
 
I. FUMIGATION WITH LIQUID 
 HYDROCYANIC ACID^ 
 
 By H. J. QUAYLE2 
 
 INTRODUCTION 
 
 Liquid hydrocj^aiiic acid^ was first used largely in experimental 
 tests in 1916 and on an extensive commercial basis in 1917 for the 
 fumigation of citrus trees in California.^ The inauguration of this 
 new method of fumigation has brought up a number of points on 
 which information is needed. Among the more important of these 
 from the standpoint of the grower and fumigator are : the killing 
 efficiency as compared with the pot and machine methods of generation 
 of the gas ; the diffusion of the gas under the tent ; effect of temper- 
 ature and humidity on such diffusion ; possible injury to the fruit and 
 foliage ; injury when the liquid itself comes in contact with different 
 parts of the tree ; the action of the liquid on the tents ; the best methods 
 of handling the liquid in the field ; the precautions to be observed in 
 such handling; and the cost of the liquid method as compared with 
 other methods of fumigation. An attempt is made in the following 
 pages to give some information on these points as based on two seasons* 
 experience with liquid hydrocj^anic acid. Other important questions 
 related to the physical and chemical properties of the material are 
 discussed in Part II of this bulletin. 
 
 1 Paper no. 58, University of California, Graduate School of Tropical Agriculture 
 and Citrus Experiment Station, Eiverside, California. 
 
 2 Acknowledgment is made of the assistance of Mr. A. F. Swain in 1917 and 
 Mr. Hugh Knight in 1918 in carrying on the experiments on which this bulletin 
 is based. 
 
 3 Hydrocyanic acid (HCN) is a liquid, but since it has never been used until 
 recently in this form for fumigation purposes it seems necessary, to avoid con- 
 fusion, to add the superfluous word ''liquid". The term for the same material 
 which has gained common practical acceptance is ' ' liquid gas, ' ' which appears 
 to be still less desirable. Another name wlich would correctly apply is ''prussic 
 acid. ' ' 
 
 4 Under the title ' ' Anhydrous Liquid Hydrocyanic Acid for Fumigation 
 Purposes," Mr. C. W. Mally published an article in the South African Journal 
 of Science for October, 1915, giving an account of fi^migation tests for the 
 mealy bug, Pseudococcus capensis, on the grape. This is the first record of the 
 use of hydrocyanic acid as a liquid for fumigation purposes that has come to 
 our notice. 
 
394 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 Some of the first tests with cyanide fumigation for citrus trees in 
 1886 involved the use of a generator outside of the tented tree.^ This 
 outside generator w^as soon discarded for earthenware pots, which 
 were placed under each tree, and the pot method of generation was 
 in use exclusively until the season of 1914, when the outside generator 
 was again adopted. This portable generator,*^ however, was very 
 different from the crude generator of 1886. It was known as the 
 ' ' Owl Fumigating Machine, ' ''^ and this generator utilized for the first 
 time a solution of sodium cyanide. During the last two or three years 
 the portable generator known as the "Cyanofumer", an improved 
 machine, has been widely used. These older methods promise to be 
 largely, if not entirely, supplanted in the near future by the use of 
 liquid hydrocyanic acid. 
 
 NATUEE OF LIQUID HYDEOCYANIC ACID AND PEECAUTIONS TO BE 
 
 OBSEEVED IN HANDLING IT 
 
 Liquid hydrocyanic acid has been known to chemists for many 
 years, but probably because of its instability and its very poisonous 
 nature, as well as the heretofore little actual need thereof, it has not 
 been manufactured on a large scale. It is a colorless liquid, less than 
 three-fourths the weight of water, having a specific gravity of 0.6969 
 at 18° C. It is also very volatile and boils at a temperature of 26.5 C 
 or 79.7 F.« 
 
 Because of its very high volatility, hydrocyanic acid gas is rapidly 
 given off from the surface of the liquid, and thus there is danger in 
 breathing in an atmosphere close to an open container. More gas 
 will be given off as the surface of the liquid is increased and also in 
 higher temperatures. The greatest surface is provided, and hence 
 there is greatest danger when the liquid is sprayed or spattered. If 
 there is any appreciable movement of the atmosphere the operator is 
 reasonably safe if he keeps to the windward side of the exposed liquid. 
 In any operation giving the material an opportunity to vaporize, such 
 as filling or emptying the machine or containers, the apparatus should 
 
 ^ Morse, F. W., The Use of Gases against Scale Insects. Bull. 71, California 
 Agricultural Experiment Station, 1886. 
 
 G Gray, Geo. P., New Fumigating Machines. Monthly Bull. California State 
 Commission of Horticulture, vol. 4, no. 2, p. 68. 
 
 7 This machine was invented by Mr. Wm. Din*;le of Los Angeles, and Mr. 
 Dingle, together with his brother, Irwin Dingle, also deserve the credit fr^ the 
 inauguration, on a commercial basis, of the use of liquid hydrocyanic acid. 
 
 8 The Cyanide Industry by Eobine & Lenglen, translated by Le Clerc, p. 16, 
 1906. 
 
FUMIGATION WITH LIQUID HYDROCYANIC ACID 395 
 
 be arranged so that it is unnecessary for the operator to hold any- 
 thing in place, and thus to avoid danger. Since the vapor is inflam- 
 mable, flame-lights should be kept away from near the exposed liquid. 
 
 Liquid hydrocyanic acid should be kept as cool as possible, and 
 under ordinary circumstances this can be done by surrounding the 
 container with cloth or sacking which is kept continuously moist. 
 The containers should be in the shade and preferably where there is 
 a free circulation of air. If the liquid is spilled on the hands there 
 is no danger (if there are no cuts or abrasions) from the actual contact 
 of the liquid, though there may be danger from the gas given off. 
 
 From our experience in the field, the most important precaution 
 (and it would seem the most needless to mention) for^ operators to 
 observe in the handling of liquid hydrocyanic acid is not to inhale 
 in an atmosphere highly charged with the gas, and therefore to turn 
 away when any liquid is exposed or get into the fresh air before 
 inhaling again. For emergencies a gas mask may be a desirable part 
 of the equipment of a fumigation crew. 
 
 THE PLANT FOR THE MANUFACTURE OF LIQUID HYDROCYANIC ACID 
 
 The first unit of the original plant for the manufacture of liquid 
 hydrocyanic acid in California or elsewhere, on a commercial scale, 
 is shown in figure 1. The process is comparatively simple. All that 
 is necessary is to subject the gas, which is generated in the usual way, 
 to a sufficiently low temperature, when it will condense even without 
 pressure, or only such pressure as is exerted by the gas itself in the 
 process of generation. The plant (see fig. 2) consists essentially of 
 generators for the generation of the gas from sodium cyanide, sulfuric 
 acid, and water, and a condensing system where the gas is conducted 
 into numerous flues which are bathed in cold brine from the refriger- 
 ation plant. The first product, which contains considerable water, is 
 then distilled, which process separates most of the hydrocyanic acid 
 from the water, yielding a product having a purity of 95 per cent or 
 higher. 
 
 The improvement possible in the present plant is to reduce the 
 waste in the liquefaction process in order that a greater amount may 
 be recovered from a given amount of sodium cyanide. During the 
 past year approximately 80 per cent of the total cyanogen has been 
 recovered, which is equivalent to about 14.8 gallons or 86 pounds of 
 the anhydrous liquid from a case. The total weight of anhydrous 
 hydrocyanic acid in a case of 200 pounds of sodium cyanide (51-52 
 
396 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 per cent cyanogen) is 108 pounds.^ It is scarcely possible, commer- 
 cially, to recover the total amount of 108 pounds from 200 pounds of 
 sodium cyanide, although this amount will be more nearly approached 
 as more improvements are made in the plant. 
 
 r ' '- 
 ■> • 
 
 4 * ^fl 
 
 .^li 
 
 
 *«--*;.v"'^? 
 
 ' -^ , I'M 
 
 
 III 
 
 
 Fig. 1 — First unit of original plant for the manufacture of liquid hydrocyanic 
 acid. Azusa, California. May, 1917. 
 
 THE ATOMIZING MACHINE 
 
 After the liquid is transported from the central plant to the field 
 in proper containers it is placed in a machine, such as is indicated in 
 figures 3 and 4. The atomizing machine consists of a tank holding 
 two and one-half gallons of the liquid, a graduate for the measurement 
 of the dosage, and a pump and spray nozzles for the atomizing of the 
 liquid. By the upward stroke of the plunger, near the graduated 
 scale (see fig. 4), the liquid is allowed to run into the graduate and 
 by the downward stroke it is forced into the coil as shown. Then 
 by the operation of the air pump on the right the liquid is forced out 
 through nozzles at the end of the exit tube into a fine misty spray, 
 which is immediately transformed into a gas. 
 
 » See Table I in Part II of this bulletin. 
 
FUMIGATION WITH LIQUID HYDROCYANIC ACID 
 
 397 
 
398 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 GEADUATION AND OPEEATION OF THE ATOMIZING MACHINE 
 
 The atomizing machine in use during the season of 1918 was 
 graduated on the basis of the recovery of 14 gallons of liquid hydro- 
 cyanic acid from 200 pounds of cyanide; that is, the liquid recovered 
 was made to go as far, according to our present schedules of dosage, 
 as the original case of cyanide by other methods of generation. There 
 are 3200 ounces in a case of sodium cyanide and 1792 fluid ounces 
 
 Fig. 3 — Atomizing machine, in use season of 1917, for atomizing liquid hydro- 
 cyanic acid under tent. 
 
 in 14 gallons. This amount of fluid was therefore divided into 3200 
 parts, so that .560 fluid ounce was used as the equivalent of 1 ounce 
 of the solid sodium cyanide. The actual amount of hydrocyanic acid 
 in .56 fluid ounce of 95 per cent hydrocyanic acid may be calculated 
 from the data in Table I, Part II, as follows : 
 
 Fourteen gallons of liquid of this purity weighs 5.956 X 14 X 16, 
 or 1334 ounces, but only 95 per cent of this weight is hydrocyanic 
 acid, the remainder being impurities, mostly water. The amount of 
 absolute hydrocyanic acid is 1334 X -95, or 1265.4 ounces. Dividing 
 this by 3200, we obtain .395 as the weight in ounces of actual hydro- 
 cyanic acid in the .560 fluid ounce of liquid delivered by the atomizer 
 as the equivalent of 1 ounce of sodium cyanide. 
 
FUMIGATION WITH LIQUID HYDROCYANIC ACID 
 
 399 
 
 By other methods of generation, the pot and portable generator, 
 we assume that about 90 per cent, at least, of the total gas is evolved.^^ 
 Under this assumption, 1 ounce of sodium cyanide would yield a 
 weight of .486 ounce of absolute hydrocyanic acid. If this amount 
 were converted into a liquid containing 5 per cent of water the volume 
 would be .693 fluid ounce. 
 
 The dosage applied by the liquid system has been only 80 per cent 
 of that applied by the older methods. If the same dosage is to be 
 
 'IHtf^*^1iwwi 
 
 Fig. 4 — Atomizing machine in use season of 1918. 
 
 applied, .693 fluid ounce of 95 per cent liquid (or .675 fluid ounce of 
 98 per cent liquid) must be used as the equivalent of the yield from 
 1 ounce of sodium cyanide when the gas is generated by the older 
 methods. 
 
 The above figures have all been given in the American system of 
 weights and measures. More finely graduated cylinders can be ob- 
 tained, marked in cubic centimeters and fractions, and are commonly 
 used to test the accuracy of delivery from the atomizing machine. 
 
 10 H. D. Young, as reported in Circular 139 of the California Agricultural 
 Experiment Station, determined that the Cyanofumer yielded, under the best 
 working conditions, about 95 per cent of the total gas. It has usually been 
 assumed that the yield from the pot method varied from 85 to 95 per cent. As 
 a conservative average of both methods we have given, as above, a 90 per cent 
 yield. 
 
400 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 The following metric equivalents will be useful in checking up their 
 delivery. 
 
 .693 fluid oz. = 20.5 c.c. (full dose of 95% HCN). 
 .675 fluid oz. = 19.9 c.c. (full dose of 98% HCN). 
 .560 fluid oz. = 16.5 c.c. (80% dose as applied last season). 
 
 To insure proper dosage, it is important that the atomizing 
 machine be kept in good working order. The machine should be 
 emptied of the hydrocyanic acid after each night's run to avoid 
 unnecessary action of the material on the parts of the machine, and 
 the machine allowed to remain filled with water until it is used again. 
 The machine should be tested frequently to see that the dose, as 
 graduated, is delivered at the end of the exit tube. This is readily 
 done by removing the nozzles and attaching a short piece of rubber 
 tubing to conduct the liquid into a suitably marked graduate. If, 
 for instance, an ounce on the graduate of the machine represents 
 16.5 cubic centimeters, when the machine is set for a 10-ounce charge 
 there should be 165 cubic centimeters delivered into the graduate. 
 A convenient graduate is furnished by running a 10-ounce charge 
 into a long, narrow bottle and marking the height of the liquid by 
 means of a file. Water may be used in measuring the accuracy of 
 the pump, but there may be more water actually delivered than liquid 
 hydrocyanic acid, so that it is more accurate to use the liquid itself, 
 in which case the proper precautions regarding safety must be kept 
 in mind. 
 
 EFFECT OF LIQCTID HYDEOCYANIC ACID ON THE FRUIT AND FOLIAGE 
 
 Gas from liquid hydrocyanic acid will injure the fruit and foliage 
 if used in excess in much the same way as the gas generated by other 
 methods. In many cases, however, particularly if the fumigation is 
 done during low temperatures, the injury is often greater in the 
 lower than in the upper half of the tree. This is accounted for under 
 ''Diffusion of the Gas." 
 
 When the liquid itself comes in contact with fruit or foliage severe 
 burning occurs, as may be seen where the material is atomized in 
 delivering the charge under the tent. This is not very serious, but 
 in the case of much low-hanging fruit it is of some consequence. Such 
 injury may be partly avoided by having a longer exit tube and ad- 
 justing the nozzles to direct the spray at a smaller angle, so as to 
 avoid the fringe of low-hanging fruit and foliage around the outside 
 of the tree. There is no danger if the liquid strikes the trunk, at 
 
FUMIGATION WITH LIQUID HYDROCYANIC ACID 401 
 
 least of old trees. We have applied the spray directly to the trunk 
 of two-year-old trees also without doing any injury. Possibly under 
 conditions very unfavorable to evaporation, as during cold and wet 
 weather, some injury might occur to the trunk of young trees. 
 
 EFFECT OF LIQUID HYDEOCYANIC ACID ON TENTS 
 
 One of the objections of the older methods of fumigation was the 
 injury that was often done to tents. Liquid hydrocyanic acid has no 
 effect on fabrics and there is no residue or acid anywhere around that 
 may do such injury. 
 
 COST OF USING LIQUID HYDEOCYANIC ACID AS COMPAEED WITH 
 THE OTHEE METHODS OF FUMIGATION 
 
 During the past tAvo years there has been little difference in the 
 cost of using the liquid as compared with the other methods of fumi- 
 gation. Distance from the manufacturing plant and other factors 
 make the cost variable. However, when the manufacture of the liquid 
 is better stabilized the cost of fumigation should be appreciably re- 
 duced. Even if the actual material will not cost less, there will be a 
 saving on the tents as well as less expense in handling the liquid in 
 the field. 
 
 When sodium cyanide (51-52 per cent cyanogen) is worth thirty 
 cents per pound, the absolute liquid hydrocyanic acid would be worth 
 fifty-five and five-ninths cents per pound. But it is not possible, 
 commercially, to recover 100 per cent, and, moreover, the product 
 recovered would not have a purity of 100 per cent. Neither is the 
 cost of liquefaction included in the above price. 
 
 If but 90 per cent is recovered in the liquid form, the corresponding 
 price (solid cyanide at thirty cents) of the liquid would be sixty- two 
 cents per pound. When a 90 per cent recovery contains 5 per cent 
 water, the corresponding price per pound of the liquid would be be- 
 tween fifty-eight and fifty-nine cents per pound. 
 
 DIFFUSION OF THE GAS 
 
 From previous experiments^^ it has been shown that with the gas 
 generated by the pot or portable generator there is a greater concen- 
 tration of the gas in the upper half of the tree, and consequently 
 
 11 Quayle, H. J., Cyanide Fumigation — Diffusion of Gas Under Tent and 
 Shape of Tree in Eelation to Dosage. Jour. Economic Entomology, vol. 11, 
 no. 3, p. 294, 1918. 
 
402 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
 better results on the scale insects in that part of the tree. "With the 
 gas which arises from the liquid under present manipulations the 
 conditions are exactly reversed and the better results occur in the 
 lower half of the tree. Of the three locations — top, center, and bottom 
 of the tree — the gas from the liquid is most effective at the bottom, 
 next at the center, and least at the top. With the pot generation 
 there is not much difference in effectiveness between the top and 
 center of an average sized tree, but there is a decided decrease in 
 effectiveness at the bottom. 
 
 In field work the lower half of the tree is examined. The upper 
 half, and particularly the top of the tree, is not examined unless some 
 special effort is made. This fact is actually favorable to the results 
 with the liquid and unfavorable to the results with the pots or port- 
 able generator. But there are more scales, in most cases, in the lower 
 than in the upper half of the tree. 
 
 In 1917 an amount of liquid hydrocyanic acid equal to only 60 
 per cent of the total gas in a given amount of cyanide was compared 
 with 90 per cent of the total gas from the same amount generated by 
 the pot or portable generator. There was no difference in results by 
 the ordinary field examination, but there was a marked difference in 
 results by our own tests. In judging the results of the liquid as com- 
 pared with other methods of fumigation in the field, therefore, allow- 
 ance must be made for the necessary inaccuracy of tests under field 
 conditions, and also for the fact that the examination is made in the 
 lower half of the tree, where the liquid is more effective. 
 
 The manner of diffusion of hydrocyanic acid gas is different 
 according to whether it comes from liquid hydrocyanic acid or from 
 a generator where the cyanide, sulfuric acid, and water are combined. 
 In the former case, vaporization takes place near the ground and 
 the gas gradually diffuses upward ; while in the latter the gas goes 
 quickly to the top of the tree and gradually diffuses downward. This 
 has been shown by the effects of the gas in first overcoming active 
 insects at the bottom of the tree in one case and at the top of the tree 
 in the other. And if the exposure is prolonged for an hour the final 
 effect on the insects shows the same difference ; that is, in the latter 
 case more recover at the bottom and in the former case more recover 
 at the top. 
 
 The manner of diffusion of the gas from the liquid, as explained 
 above, is better adapted, we believe, to the killing of scales on the tree 
 than the manner of diffusion from the pot or portable generator, 
 particularly since most of the scales occur in the lower part of the 
 tree, and for this reason it is possible that the liquid equivalent may 
 
FUMIGATION WITH LIQUID HYDROCYANIC ACID 403 
 
 be slightly reduced. The question may properly be raised whether 
 more scales occur in the lower half of the tree because the older 
 methods of fumigation failed to kill them as well there, but we believe 
 that the habits of the insects also favor that location. 
 
 EFFECT OF TEMPERATURE ON DIFFUSION OF HYDROCYANIC 
 
 ACID GAS 
 
 The question of temperature may be more vitally concerned with 
 the diffusion of gas from the liquid than from the pot or portable 
 generator, although it is a factor in any method of fumigation. The 
 higher temperatures hasten the vaporization and diffusion of gas from 
 the liquid and insure a better killing at the top of the tree. On the 
 other hand, the higher temperatures aid in the diffusion of the gas 
 downward with the pot method where it is first concentrated in the 
 top of the tree. Our experiments have pointed strikingly to the 
 tendency that the higher the temperature the more uniform is the 
 distribution in all parts of the tree. As the temperature decreases 
 the divergence in results increases between the top and bottom of the 
 tree, in case of the liquid in favor of the bottom and in case of the pot 
 in favor of the top of the tree. 
 
 In the pot or portable generator the actual gas is produced more 
 or less regardless of the atmospheric temperature, since the different 
 chemicals when brought in contact will act upon one another to gen- 
 erate the gas, during which action heat is also produced, and the 
 warm gas readily rises. With the liquid vaporization must first occur, 
 and low temperature, as well as high humidity, tends to retard such 
 action. Moreover, when the gas is actually formed it is a cold gas 
 and has a smaller tendency to rise in the tent. The atomizing of the 
 liquid is in itself a cooling process. The bulb of a thermometer when 
 held for a few moments before the nozzles as liquid hydrocyanic acid 
 was being atomized showed a drop in temperature from 70° F to 
 —4° F. 
 
 The following table gives the total average '^kill" of ladybird 
 beetles in the form "frees"^^ for the 1918 series of tests, which ex- 
 tended over four months and included the use of about 25,000 insects. 
 
 Bottom and center Top and center 
 
 of tent of tent 
 
 Pot 85.7% killed 91.1% killed 
 
 Liquid 83.8% killed 76.9% killed 
 
 12 The form 'Hrees" consisted of a framework of wood in the shape of an 
 ordinary citrus tree over which were placed ordinary fumigation tents. The 
 dimensions were 26 X ^1> thus representing fair sized trees. 
 
404 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 From the above it will be noted that the discrepancy in efficiency 
 with the liquid occurs in the upper half of the tree. But the experi- 
 ments also showed that this discrepancy was greatly reduced with the 
 higher temperatures. Another tendency that has been indicated is: 
 that a long exposure increases the effect of the gas from the liquid. 
 This may be due to the slower diffusion, as well as the cooler gas from 
 the liquid actually escaping more slowly through the tent. By the 
 other methods of fumigation it is quite well established that there is 
 no value in increasing the time of exposure beyond about forty-five 
 minutes. 
 
 As to whether the tendency of the gas from the liquid to remain 
 largely in the lower half of the tree during low temperatures is a 
 serious objection to its practical use, or whether it is practicable to 
 increase the exposure, remains for further experience to determine. 
 Heating the gas, or a better system of atomizing, or gasifying the 
 liquid, are two possible ways of overcoming the poor diffusion, although 
 this might complicate the field manipulations. 
 
 THE EFFICIENCY OF LIQUID HYDROCYANIC ACID AS COMPARED 
 WITH POT AND MACHINE GENERATION 
 
 The killing efficiency of the liquid as compared with other methods 
 of fumigation was determined: {a) by comparative tests in a fuma- 
 torium; (&) by comparative tests under form trees; (c) by compar- 
 ative tests in the field; and {d) by examination of commercial work 
 in the field. 
 
 In addition to the scale insects of citrus trees, for which pests 
 fumigation work is carried on, ladybird beetles were used as an index 
 of the results. Our two seasons' work with the beetles lead us to 
 conclude that they are more desirable than scale insects as furnishing 
 a sharp index of comparative fumigation results. In the case of scale 
 insects, there may be 100 per cent killed with ordinary dosages, where 
 these dosages vary as much as 25 per cent. With the highest dosage 
 that may be used with safety to the citrus trees, some of the beetles 
 will survive, and increasing numbers will survive as the dose is de- 
 creased. It is possible also to determine the difference in results be- 
 tween the top and bottom of a tree, with the beetles properly placed, 
 while with the scale insects occurring naturally on the tree it is more 
 difficult to make such a distinction. All of our results, however, are 
 based on work both with the beetles and the scale insects. 
 
 During the season of 1917, in our tests both in the field and under 
 form trees, the results with the liquid were less satisfactory than the 
 results carried on at the same time with the pot and cyanofumer. 
 
FUMIGATION WITH LIQUID HYDROCYANIC ACID 405 
 
 This may be accounted for from the fact that during that season the 
 liquid was not of high purity until late in the season, and also because 
 the machine in use that year was graduated on the recovery of only 
 12% gallons of liquid from a case of cyanide. In our examination 
 of commercial fumigation, however, there was little if any difference 
 that could be determined by the results on the scales in the field. 
 
 During the season of 1918 our own tests again showed that the 
 liquid was slightly less efficient than the pot method, although there 
 was a marked improvement over the preceding year. In the field, 
 as in 1917, no appreciable difference could be distinguished. Tests 
 carried on with the cyanofumer and liquid on alternate trees in the 
 same tent-throw, thus insuring similar conditions, failed to distinguish 
 any difference either on beetles which were placed in the tree or on 
 the scales on the fruit and foliage. The results thus determined, 
 however, represent the effect on the insects within six or eight feet of 
 the ground, which fact is important as discussed under the head of 
 "Diffusion of the Gas." 
 
 In our experiments with form "trees" the difference between the 
 pot and liquid methods was brought out by considering the effect of 
 the gas at three different points, namely, one foot from the top, one 
 foot from the bottom, and in the center of the tree. When the results 
 in the lower half only were considered, there was no important dif- 
 ference between the pot and liquid methods. But when the results 
 on the upper part of the tree were included, they were more favorable 
 to the pot method. 
 
 While, so far as field conditions and examination go within seven 
 or eight feet of the ground, between the liquid and the older methods 
 of fumigation the results have shown little important difference, we 
 believe that a greater recovery of liquid from a given amount of 
 cyanide is necessary, and that it is desirable to increase the amount 
 given to the tree over that of the past two years. Judging from the 
 field work, we had come to believe that when temperature conditions 
 are favorable the gas from the liquid must be 10 to 15 per cent more 
 effective than the same amount of gas from the pot or portable gen- 
 erator. Fourteen gallons of liquid hydrocyanic acid of 96 or 98 per 
 cent purity recovered from 200 pounds of sodium cyanide represent 
 only 75 per cent of the total available gas, while by the other methods 
 90 per cent of the total gas in 200 pounds was recovered, making a 
 difference of 15 per cent. Yet, during the past year, the 14 gallons 
 of liquid was made to cover the same ground as 200 pounds of 
 sodium cyanide generated by the other methods. When the results 
 in all parts of the tree are considered, however, as shown by our 
 
406 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 comparative tests for two seasons, we believe that, under normal con- 
 ditions, practically the equivalent in the actual amount of gas must be 
 used to effect the same results regardless of whether the source of the 
 gas is from liquid hydrocyanic acid or from the pot or portable 
 generator. Consequently 90 per cent at least, representing 17 gallons 
 or 100 pounds of liquid hydrocyanic of 96 or 97 per cent purity, 
 should be recovered from 200 pounds of sodium cyanide, and this 
 amount should be made to cover the same ground as 200 pounds of 
 sodium cyanide on the basis of the dosage schedules now in use. This 
 would be equivalent to using approximately 20 cubic centimeters to 
 correspond to one ounce of sodium cyanide (51-52 per cent cyanogen). 
 (See discussion under ^'Graduation and Operation of Atomizing 
 Machines," p. 398 and table 1, p. 412.) 
 
 SUMMARY AND CONCLUSIONS 
 
 Liquid hydrocyanic acid, a new means of citrus fumigation, first 
 used on a commercial basis in 1917, has rapidly come into favor. 
 
 The place where the greatest concentration of gas occurs under 
 the tent from the liquid is practically the reverse of that from the pot 
 or portable generator. 
 
 "With the former method the most effective killing is at the bottom 
 of the tree, while with the latter the most effective killing is at the top. 
 
 Aside from the scale insects, more than 75,000 ladybird beetles 
 have been used in our comparative tests as an index of results. 
 
 The use of these insects has given discriminating data concerning 
 the diffusion of gas under the tent, as well as on the efficiency of the 
 different methods of fumigation, and these data have been verified by 
 extensive field tests. 
 
 The greatest possible yield is 108 pounds or 18.56 gallons of an- 
 hydrous liquid hydrocyanic acid from 200 pounds of sodium cyanide 
 (51-52 per cent cyanogen). 
 
 The amount of liquid hydrocyanic acid (95-98 per cent) that has 
 been recovered at the plant during the past year has been about 78 
 per cent of the total available. 
 
 The amount of gas evolved by the pot or portable generator is 
 estimated at 90 per cent of the total available gas. 
 
 During the past year 75 per cent of the gas from a given amount 
 of cyanide in the liquid form was made to cover the same ground as 90 
 per cent from the same amount by the ordinary methods of generation. 
 
FUMIGATION WITH LIQUID HYDROCYANIC ACID 407 
 
 Thus, while there has been a discrepancy of 10 or 15 per cent in 
 the actual amount of gas used through the liquid method, the results 
 in the field have not indicated any important difference on the scale 
 insects. 
 
 Our own tests, however, both in the field and laboratory, have 
 indicated about such difference as would be expected. 
 
 This apparent discrepancy between our own tests and commercial 
 work in the field may be accounted for through the great variability 
 in field work and by the difference, as has been determined, in the 
 diffusion of the gas from the different methods. 
 
 Field examinations are usually limited to an examination of the 
 scales within six or eight feet of the ground. 
 
 Our own tests have included the top of the tree as well. From 
 these tests, when the results at the center and the bottom only were 
 considered, there was practically no difference between the liquid and 
 the pot, which harmonizes with the results in the field. 
 
 When the results at the center and top only were considered, the 
 pot method was more efficient than the liquid method. 
 
 When the results in all parts of the tree are considered, it is 
 necessary to use about 20 cubic centimeters of liquid hydrocyanic 
 acid (96 or 98 per cent) to equal one ounce of sodium cyanide as 
 given in the schedules of dosage now in practical use. 
 
 Units representing 20 cubic centimeters may therefore be sub- 
 stituted for the ounces, and the atomizing machines should be gradu- 
 ated to deliver 20 cubic centimeters for each ounce called for in the 
 schedules. 
 
II. PHYSICAL AND CHEMICAL PROPERTIES 
 OF LIQUID HYDROCYANIC ACID 
 
 By GEO. P. GRAY and E. R. HULBIRTi 
 
 The ready acceptance of liquid hydrocyanic acid hy fumigators 
 during the first year of its commercial production strongly empha- 
 sized the need of a better knowledge of the physical and chemical 
 properties of a liquid of such unusual characteristics. The Fruit 
 Growers' Supply Company, the purchasing organization of the 
 •California Fruit Growers' Exchange, were much concerned over the 
 scarcity of information regarding the liquid being marketed, and 
 financed an investigation of the plant and product of the Owl Fumi- 
 gating Company at Azusa, California, during the month of August, 
 1918. This preliminary investigation not only proved to be of much 
 value to the growers but also disclosed such a variety of questions 
 to be answered that a co-operative arrangement for the continuation 
 of the investigation was made between the supply company and this 
 laboratory. The following pages constitute a report of these investi- 
 gations. - 
 
 COMMERCIAL CONSIDERATIONS 
 
 The questions of most immediate concern appeared to be of a 
 commercial nature. The liquid being delivered to consumers was not 
 sold outright, but was delivered upon an exchange basis. The fumi- 
 gators purchased their own sodium cyanide and brought it to the plant 
 
 1 Co-operating chemist, representing the Fruit Growers ' Supply Company. 
 
 2 The writers wish to express their appreciation of the attitude of Messrs. 
 Ervin and WilHam Dingle, who have extended to them every courtesy during 
 the course of the investigation and have given them the freedom of their plant, 
 and have done everything in their power to facilitate the work. The Board of 
 Trustees and Professor F. S. Hayden, Principal of the Citrus Union High School, 
 have generously allowed the free use of their laboratories and apparatus. This 
 accommodation has greatly facilitated the investigation by allowing the testing 
 laboratory and the liquifying plant to be located in close proximity. The 
 interest shown by Mr. R. S. Woglum and Mr. H. D. Young of the United States 
 Bureau of Entomology in developing methods of analysis and in the test runs 
 of the plant has been of great assistance. Mr. F. W. Braun, Mr. M. B. Pattison, 
 and Mr. J. D. Neuls of the Braun Corporation have offered many suggestions, 
 jjarticularly concerning methods of analysis. The many accommodations and 
 courtesies extended by Mr. C. C. Hillis, Mr. C. A. Savage, and other officials of 
 the Azusa-Covina-Gleudora Fruit Exchange are much appreciated. 
 
PHYSICAL AND CHEMICAL PROPERTIES OF HYDROCYANIC ACID 409 
 
 for treatment. The plant furnished the sulfuric acid, generated, and 
 liquefied the hydrocyanic acid at a fixed charge per case of sodium 
 C3^anide. There appeared to be no well established idea as to what 
 quantity of liquid should be recovered from a case of sodium cyanide 
 under the operating conditions of the plant, though it was generally 
 conceded that the quality of the liquid being delivered to the consumer 
 was of good grade. 
 
 Test Buns. — In order to determine the amount and quality of 
 liquid recovered from a case of sodium cyanide under the operating 
 conditions of the plant, the owners offered to make a test run to be 
 carried on under the supervision of a representative of the Fruit 
 Growers' Supply Company. The results of these tests were to be 
 used as a basis of settlement between fumigator and plant. In order 
 that the results should be above criticism of partiality, the following 
 gentlemen kindly accepted an invitation to be present to witness the test 
 run : Messrs. R. S. Woglum, entomologist, and H. D. Young, chemist, 
 representing the U. S. Bureau of Entomology ; Professor H. J. Quayle, 
 entomologist, representing the Citrus Experiment Station of the Uni- 
 versity of California ; Mr. W. C. Bass, chemist, representing the Owl 
 Fumigating Company ; and the senior writer, representing the Fruit 
 Growers' Supply Company, and unofficially the Insecticide and Fungi- 
 cide Laboratory of the University of California. The proposed pro- 
 cedure of the test was outlined and agreed upon by the representatives 
 present as being a fair one. Seventeen cases of sodium cyanide 
 (3400 pounds) were weighed out and sampled for the test run. The 
 plant was operated in the usual manner and the yield of liquid was 
 weighed and sampled. The samples noted above were independently 
 analyzed by Messrs. Young, Bass, and Gray. On comparing the 
 results of analysis it was found that the three sets of results were 
 in essential agreement. Not being willing to base conclusions upon 
 a single run of the plant, another test was made a week later in a 
 similar manner. The liquid hydrocyanic acid recovered in the first 
 test run was 80.1 per cent of the greatest possible yield; in the second, 
 76.3 per cent ; an average of 78.2 per cent. The average purity of the 
 liquid obtained in the first run was 97.57 per cent ; in the second, 
 94.27 per cent. 
 
 While the yield of 78 per cent was quite disappointing, it must 
 be recognized that this is an infant industry, and that with increasing 
 knowledge and experience with the liquid continual improvement in 
 all phases of its manufacture and use may be expected. The con- 
 structors of the plant had no previous work to guide them in selection 
 of their equipment. There were certain evident losses in the operation 
 
410 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
 of the plant which will doubtless be remedied before next season. 
 It also appears that there are certain other losses, the causes of which 
 are somewhat obscure. 
 
 Quality of Liquid. — Frequent analyses and tests have been made 
 of the liquid being delivered to consumers, covering a period from 
 the first of August to the close of the fumigating season. The average 
 purity of the liquid delivered to consumers has been above 95 per cent 
 absolute hydrocyanic acid. Occasional drums of liquid have been 
 noted which were considerably below this figure. After the plant 
 was supplied with hydrometers so that the purity of the output could 
 be quickly approximated, the delivery of a low-grade drum of liquid 
 was rare. Liquid testing considerably below 95 per cent was returned 
 to the crude liquid storage tank and redistilled. 
 
 The writers are as yet undecided as to the comparative merits of 
 a liquid testing, say, 95 per cent and one testing, say, 98 per cent or 
 more. It is even maintained by some fumigators that the high per- 
 centage of liquid is too volatile for safe handling, and that they much 
 prefer a liquid testing 95 to 96 per cent. The definite determination 
 of this point must be made by future investigation. In the present 
 state of our knowledge, it is believed that a material testing 95 per cent 
 or more of hydrocyanic acid is of a satisfactory grade. The plant as 
 operating at present is quite capable of and does produce liquid of 
 this quality, or better, many samples testing over 98 per cent. 
 
 Return Per Case. — As the plant was operated during the past 
 season and based upon the investigation reported above, the following 
 is believed to be a fair return per case of two hundred pounds of 
 sodium cyanide, testing 96-98 per cent of sodium cyanide : 
 
 1. A minimum of 85 pounds of absolute hydrocyanic acid ; or 
 
 2. A minimum of 90 pounds of liquid testing not less than 95 per 
 cent hydrocyanic acid. 
 
 Liquid of 95 per cent purity should not test less than 66° on the 
 Baume hydrometer at a temperature of 60° Fahrenheit, corresponding 
 to a specific gravity of .715. A gallon of liquid of this density would 
 weigh 5.956 pounds. 
 
 The above must not be taken as final. As the necessary infor- 
 mation is accumulated it is confidently anticipated that the yield in the 
 future will be equal to or even greater than that now obtained from 
 the portable generators in common use. 
 
 . Weight Basis. — Settlements are now made on a basis of gallons of 
 liquid returned per case of sodium cyanide delivered. The liquid can 
 be fairly easily measured when delivered to the consumer by an 
 automatic measuring device, but measuring of so volatile and poisonous 
 
PHYSICAL AND CHEMICAL PROPERTIES OF HYDROCYANIC ACID 411 
 
 a liquid without such a device is a rather dangerous undertaking 
 and is not so easily subject to accuracy as weighing. It is strongly 
 urged that the weight basis be adopted in transactions dealing with 
 liquid hydrocyanic acid. The strongest argument in its favor is that 
 the consumer would have a ready and convenient means of checking 
 up deliveries. The weight of the empty drum could be determined 
 and the figures painted on the drum. The weighing of the full drum 
 only requires a short time, and in that way the weight of the liquid 
 delivered would be determined by deducting the weight of the con- 
 tainer from the gross weight. An additional argument in favor of 
 the adoption of the weight basis in commercial transactions is evident 
 from the following: The weight of the recovered liquid will be the 
 same at any temperature. The corresponding number of gallons, 
 however, will vary according to the temperature of the liquid. 
 
 It has been held by some that the weight basis would place the 
 consumer at a disadvantage for the reason that a low-grade liquid 
 weighs considerably more than a high grade. It is not to be expected 
 that a commercial product could be absolutely uniform. If, however, 
 95, 96, or some other percentage were finally adopted as the minimum 
 standard of purity, the consumer would be justified in refusing any 
 material of less purity than this. Fortunately it is unnecessary to 
 have a chemical analysis made to determine purity. This can be 
 determined accurately by observing specific gravity and temperature 
 and using the appended reference tables. 
 
 Table I following will be of use in making settlements for the 
 return of liquid, in making dosage calculations, etc. The figures in 
 the table showing yield in gallons are correct when the liquid is 
 measured at a temperature of 15° C (60° F) only. 
 
412 
 
 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
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PHYSICAL AND CHEMICAL PROPERTIES OF HYDROCYANIC ACID 413 
 
 PHYSICAL PROPERTIES 
 
 Miscibility. — During the earlier stages of the commercial produc- 
 tion of the liquid it was erroneously believed that mixtures of hydro- 
 cyanic acid and water would separate on standing into layers of 
 different composition. The reason for this belief was that the first 
 run in the morning was often diluted with water remaining in the 
 condensors and conveying pipes after flushing at the end of the 
 previous day's run. As soon as this point was established it became 
 the custom at the plant to draw off the first run of low-grade liquid 
 and return it to the crude liquid receiver to be redistilled. 
 
 It has been determined that hydrocyanic acid is miscible with 
 water in all proportions. When once thoroughly mixed, the liquid 
 remains homogeneous throughout, except as affected by chemical de- 
 composition. When the two are mixed there is always an appreciable 
 contraction in volume accompanied by a fall in temperature. This 
 fact complicated the problem of determining the relation of percentage 
 purity to specific gravity and necessitated extensive experimentation, 
 as will be described under a later heading. 
 
 Evaporation. — The anhydrous liquid has a very strong affinity for 
 water, so if a high-grade liquid is exposed to moist air it will either 
 absorb moisture from the air and become dilute or, the acid being 
 more volatile than water, will evaporate at a greater rate, leaving a 
 residue of low-grade liquid. 
 
 A cylinder was filled with a much diluted and thoroughly mixed 
 sample of hydrocyanic acid. This was analyzed and then the cylindei' 
 was allowed to stand uncovered in an exposed place for fifteen hours, 
 so that evaporation might proceed readily. In that time about 30 
 per cent of the liquid had evaporated. A sample of the remaining 
 liquid was then analyzed, and the results were as follows: 
 
 Sample from cylinder at first: 46.6% hydrocyanic acid. 
 
 Sample from cylinder after evaporation: 29.4% hydrocyanic acid. 
 
 A high-grade liquid evaporates so rapidly that its temperature is 
 lowered at times even to the point where particles of ice are formed. 
 In experimenting with the liquid in a room where the temperature 
 was about 90° F, and in a good current of air, a cylinder was filled 
 with the liquid and enough more added so as to run down the sides 
 of the cylinder. The temperature of the liquid was reduced ten 
 degrees in ten minutes. This is a very desirable property, for if the 
 liquid is warmed up to near the boiling point and allowed to evaporate 
 freely it is automatically cooled and evaporation thus retarded. 
 
414 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 Vapor pressure has an important bearing on the strength of 
 materials required for containers. Apparently the vapor pressure 
 of hydrocyanic acid is very small. In other words, a comparatively 
 slight pressure is required to retain the substance in a liquid state, 
 even at temperatures near its boiling point. The writers have as 
 yet been unable to investigate this matter, but the figures shown in 
 Table II are contributed through the courtesy of Mr. W. C. Bass of 
 Los Angeles as being approximately correct. 
 
 TABLE II 
 Pressure of Hydrocyanic Acid (About 97% HCN) in a Closed Container at 
 
 Different Temperatures 
 
 Temp. deg. F 
 
 Pounds pe 
 
 87 
 
 3.4 
 
 94 
 
 4.9 
 
 100 
 
 7.9 
 
 105 
 
 9.8 
 
 110 
 
 11.8 
 
 115 
 
 13.3 
 
 120 
 
 15.7 
 
 125 
 
 17.7 
 
 SPECIFIC GRAVITY 
 
 It is important for the fumigator to know the approximate per- 
 centage of hydrocyanic acid in the liquid which he uses in order to 
 enable him to reject material of low grade. This is of special im- 
 portance if the weight basis be adopted in making settlement. The 
 sampling and analyzing of a poisonous and volatile material of this 
 sort presents unusual difficulties. Inasmuch as the density of the 
 pure liquid is less than three-fourths that of water and the principal 
 impurities which are apt to be encountered in a commercial liquid 
 are water or other impurities which are heavier than the pure liquid, 
 it was early recognized that the determination of specific gravity 
 might be utilized in approximating the percentage purity of a com- 
 mercial liquid. This view was confirmed by preliminary experiments 
 and a hydrometer spindle has been used throughout the course of 
 these investigations as a ready and satisfactory means of approxi- 
 mating purity of the output of the plant. 
 
 The specific gravity of the liquid materially changes with varying 
 temperatures. Also on account of the contraction in volume when 
 
PHYSICAL AND CHEMICAL PROPERTIES OF HYDROCYANIC ACID 415 
 
 water and acid are mixed the rate of variation varies according to 
 the percentage of water and acid in the sample. These complications, 
 however, do not interfere with the application of this method of 
 approximation, provided the extent of these variations are known. 
 
 This matter was gone into very thoroughly and data have been 
 obtained giving complete information on all of the points involved. 
 These data, presented in the reference tables at the end of this bulletin, 
 were determined by means of a hydrometer spindle accurate to the 
 third decimal place. The temperature was observed in degrees of the 
 Centigrade scale. Table VI will indicate the percentage of absolute 
 hydrocyanic acid corresponding to various densities and at a range 
 of temperature from 5° to 22° C. Hydrometer spindles graduated 
 in specific gravity are not as readily obtainable as spindles reading 
 in degrees Baume. In order to make the tables available for use 
 with a Baume hydrometer, they have all been recalculated, indicating 
 the corresponding Baume reading and the variation in temperature 
 according to the Fahrenheit thermometer. These data are given in 
 Table VII. 
 
 These determinations were all made upon the commercial liquid. 
 The specific gravity at different temperatures of 100 per cent material, 
 however, has been calculated from the data for liquids of lower per- 
 centages. It is interesting to note that the calculated specific gravity 
 at 18° C of 100 per cent acid is .6943. The commonly accepted 
 specific gravity of this material is .6967.^ The close agreement of 
 these two figures is believed to be a confirmation of the accuracy of 
 the determinations. 
 
 Thirteen samples of liquid hydrocyanic acid were selected, being 
 representative samples of the product of the liquefying plant over a 
 period of three months. Some were intentionally diluted with water. 
 The temperature of the samples was made to vary and conditions so 
 arranged that they would afford a fair measure of the accuracy of 
 the tables. The specific gravity and temperature of each were care- 
 fully observed and the percentage of hydrocyanic acid determined by 
 reference to the tables, and then by careful analysis. The results 
 are shown in Table III. The laboratory analysis is accurate to two- 
 tents of 1 per cent. Since there is no greater variation than the 
 experimental error between the percentages determined by analysis 
 and by the tables and since the conditions of the samples were made 
 quite variable, the following table is considered to be a positive justi- 
 fication of the tables and confirmation of their accuracy. 
 
 3 H. E. Williams, Chemistry of Cyanogen Compounds, and their Manufacture 
 and Estimation. J. and A. Churchill, London, 1915. 
 
Observed 
 specific gravity 
 
 Temperature 
 deg. C 
 
 .736 
 
 17 
 
 .7115 
 
 16 
 
 .704 
 
 16.5 
 
 .7045 
 
 16 
 
 .705 
 
 16 
 
 .704 
 
 16 
 
 .715 
 
 16.5 
 
 .716 
 
 16 
 
 .720 
 
 5.25 
 
 .713 
 
 10 
 
 .7405 
 
 13.5 
 
 .742 
 
 12 
 
 .7185 
 
 14 
 
 HCN 
 by tables 
 
 % 
 
 88.2 
 
 95.6 
 
 97.7 
 
 97.8 
 
 97.7 
 
 97.9 
 
 94.5 
 
 94.4 
 
 97.7 
 
 97.7 
 
 88.1 
 
 88.2 
 
 94.5 
 
 416 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
 TABLE III 
 
 Comparison of Eesults Obtained on Determination of HCN by Using Our 
 
 Eeference Tables and by Analysis 
 
 HCN 
 by analysis 
 
 % 
 
 88.2 
 95.6 
 97.8 
 97.9 
 97.7 
 98.1 
 94.7 
 94.6 
 97.7 
 97.7 
 88.2 
 88.2 
 94.7 
 
 Use of the Tables. — The tables referred to above make it possible 
 to determine the quality of the liquid in a moment's time by the use 
 of a hydrometer spindle graduated either in specific gravity or Baume 
 degrees, taking into account the temperature of the liquid. Many 
 of these spindles are provided with a thermometer, so that both 
 observations can be made from one instrument. It requires no tech- 
 nical skill to make such observations. Any one w^ithout previous 
 experience can easily read the hydrometer accurately v^^ithin one 
 degree Baume. This introduces an error of approximately 1 per cent. 
 With a little practice and with an accurately graduated instrument 
 an even closer approximation than this can be made. After the 
 hydrometer reading and the temperature of the liquid have been 
 taken, the corresponding percentage is determined by referring to 
 Table VI if the spindle reads in specific gravity or to Table VII if 
 the Baume hydrometer has been used. 
 
 The Cyanometer. — The accumulation of the data referred to above 
 has made possible the construction of a hydrometer graduated directly 
 in percentage hydrocyanic acid. The idea of such an instrument is 
 not a new one. In fact, alcoholometers, salometers, saccharometers, 
 etc., are in common factory use for the determination of alcohol in 
 mixtures of alcohol and water, salt in brine, and sugar in syrup 
 respectively. Our data have made possible the construction of a 
 ''cyanometer" to be used for a purpose similar to the above. It is 
 possible that the somewhat restricted use for these instruments might 
 not make their construction attractive to instrument makers. In this 
 case the reference tables are available. If, however, the idea appeals 
 
PHYSICAL AND CHEMICAL PROPERTIES OP HYDROCYANIC ACID 417 
 
 to the fumigators as of sufficient importance and the demand is great 
 enough, an instrument could be procured which will indicate per- 
 centages of hydrocyanic acid directly. This, of course, should be 
 provided with a thermometer and with a table of temperature cor- 
 rections. All of these data could easily be contained within the glass 
 shell of the average hydrometer. A simplified scale for the graduation 
 of this instrument as well as a table for temperature correction is 
 shown below. 
 
 
 
 TABLE IV 
 
 
 
 
 Data for Construction of the Cyanometer 
 
 
 Marked on scale 
 
 Corresponding 
 
 marks on hydrometers 
 
 Temperatu 
 
 re corrections 
 
 HCN% 
 ateO^F 
 
 Baume reading 
 at 60° F 
 
 Specific gravity 
 equivalent to Baume 
 
 A 
 
 deg. P 
 
 Corections 
 
 100 
 
 71.0 
 
 .697 
 
 70 
 
 -2% 
 
 99 
 
 69.8 
 
 .701 
 
 65 
 
 -1% 
 
 98 
 
 68.7 
 
 .705 
 
 60 
 
 
 
 97 
 
 67.8 
 
 .708 
 
 55 
 
 + 1% 
 
 96 
 
 66.9 
 
 .711 
 
 50 
 
 +2% 
 
 95 
 
 65.9 
 
 .715 
 
 45 
 
 +3% 
 
 94 
 
 65.0 
 
 .718 
 
 40 
 
 +4% 
 
 93 
 
 64.1 
 
 .72] 
 
 
 
 92 
 
 63.2 
 
 .725 
 
 
 
 91 
 
 62.3 
 
 .728 
 
 
 
 90 
 
 61.4 
 
 .732 
 
 
 
 89 
 
 60.6 
 
 .735 
 
 
 
 88 
 
 59.7 
 
 .738 
 
 
 
 87 
 
 58.8 
 
 .742 
 
 
 
 86 
 
 58.0 
 
 .745 
 
 
 
 85 
 
 57.1 
 
 .748 
 
 
 
 An instrument of this kind is commonly calibrated for use at a 
 temperature of 60° F, and is correct at that temperature only. If 
 used at any other temperature than the above the observed reading 
 should be corrected according to the variation above or below the 
 temperature at which the instrument is calibrated. 
 
 CHEMICAL PROPERTIES 
 
 Hydrocyanic Acid; Priissic Acid 
 
 Chemical Symbol, HON; Molecular Weight, 27.02 
 
 DECOMPOSITION 
 
 Most impurities tend to accelerate the decomposition of hydro- 
 cyanic acid. The purer the liquid is the better its keeping qualities. 
 Impurities may be present especially from contact with metals or in 
 
418 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
 the form of other products. These may have their origin in the manu- 
 facturing plant or in the containers used for handling and dispensing 
 the liquid. Some metals react with the liquid and the metallic cyan- 
 ides thus formed may later be precipitated, forming a troublesome 
 sediment. In some cases they can be easily removed by straining. 
 Some of the causes of decomposition are solely under the control of 
 the manufacturer, while others are under the control of the fumigator. 
 "When the liquid decomposes it forms several substances which 
 themselves accelerate decomposition of fresh liquid with which they 
 come in contact. In other words, decomposition appears to be a 
 cumulative process. Undesirable impurities may be imperceptible in 
 a freshly prepared liquid, but nevertheless have their effect. The 
 decomposition is gradual at first and is marked with the appearance 
 of a faint yellow tint and an accompanying lowering of percentage 
 of hydrocyanic acid. As this proceeds the color becomes deeper and 
 merges into brown, when the chemical changes take place more rapidly 
 and new gases are formed in great quantity. At this stage a dark 
 brown or black flaky precipitate is formed. After complete decom- 
 position the newly formed gases have escaped, leaving a bulky, black 
 sediment much resembling carbon, or, if the liquid is confined, the 
 pressure of these gases is oftentimes sufficient to burst the container. 
 The above description is well illustrated by the following record of 
 a decomposed sample. Table V. 
 
 TABLE V 
 Record of a Decomposed Sample 
 
 % HON 
 
 94.7 
 93.8 
 93.2 
 93.2 
 93.3 
 92.8 
 92.3 
 92.3 
 90.2 
 80.0 
 
 Warning Signs. — So far as observed, when a sample starts to de- 
 teriorate a color of some sort, usually yellow, is always formed. Am- 
 monia seems to be one of the gases formed in greatest quantity, or at 
 least one which can most readily be detected in decomposing hydro- 
 cyanic acid. The formation of any color or an odor of ammonia then 
 may be taken as a warning. 
 
 Analysis 
 
 Date, 1918 
 
 Color of sample 
 
 Weather 
 
 1 
 
 Oct. 
 
 Straw color 
 
 warm 
 
 2 
 
 4 
 
 Amber 
 
 warm 
 
 3 
 
 8 
 
 Amber 
 
 warm 
 
 4 
 
 14 
 
 Amber 
 
 cool 
 
 5 
 
 16 
 
 Amber 
 
 cool 
 
 6 
 
 21 
 
 Yellow 
 
 cool 
 
 7 
 
 25 
 
 Yellower 
 
 cool 
 
 8 
 
 29 
 
 Very yellow • 
 
 • cool 
 
 9 
 
 ^ ov. 2 
 
 Brownish yellow 
 
 warm 
 
 10 
 
 4 
 
 Black sludge 
 
 cool 
 
PHYSICAL AND CHEMICAL PROPERTIES OF HYDROCYANIC ACID 419 
 
 Keeping Qualities. — The question has often been asked, how long 
 the liquid will keep. This question cannot be answered easily. Some 
 samples several years old are apparently as good now as when first 
 prepared. Other samples decomposed completely within a few days 
 or weeks. One apparently good sample which was closely observed 
 completely decomposed in forty days. Another sample of similar ap- 
 pearance and kept under the same conditions was as good at the end 
 of four months as it was at first. The natural life of the liquid de- 
 pends upon its history in the course of manufacture as well as upon 
 
 conditions of handling and storage. Some of the factors influ- 
 encing the keeping qualities of the liquid are discussed below. 
 
 Dilution. — Our experiments point toward the conclusion that the 
 presence of water, especially in amounts more than 5 per cent, are 
 favorable to decomposition and tend to increase the effect of the acid 
 upon many metals. It is probable that a liquid as nearly anhydrous 
 as could be produced would be the most desirable from these stand- 
 points. The great volatility of a liquid of this nature, however, may 
 necessitate a compromise between the highest purity obtainable and 
 one more convenient to handle. 
 
 Temperature. — The liquid resists decomposition much better at low 
 temperatures, other conditions being the same, than it does at high 
 temperatures. If held in an open container it would boil at a tem- 
 perature of about 80° F. The liquid should be kept cool at all tinies, 
 preferably never becoming warmer than 60° F. If the liquid is 
 allowed to become sufficiently warm, it is very easy to see that a closed 
 drum of liquid could be burst (see Table II). Some of the explosions 
 of previous years may be partly accounted for from this cause, as well 
 as from the decomposition of the liquid producing gases of greater 
 vapor pressure than hydrocyanic acid. 
 
 Decomposition Residue. — The dark colored deposit from a partly 
 decomposed sample has been demonstrated to be highly favorable to 
 decomposition when placed in a fresh sample. This matter has an 
 important bearing on the washing out of delivery containers, atomizing 
 machinery and any other vessels used in storage or handling. Invest- 
 igations are under way in an effort to disclose some substance which 
 can be used to change the nature of this deposit so that it would not 
 be so favorable to decomposition. Sufficient progress has not been 
 made to warrant publication. 
 
 A portion of the black solid residue remaining after a sample of 
 hydrocyanic acid had completely decomposed was spread out and left 
 exposed to the air for three weeks. At the end of that time some of 
 this solid, resembling charcoal in appearance, was added to some hydro- 
 
420 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 cyanic acid in a small flask and set away. The liquid became slightly 
 yellow as soon as the material had settled. Within one day the liquid 
 was brownish yellow ; in four days, brown and throwing down a de- 
 posit ; within two weeks, the liquid had completely decomposed. The 
 same lot of liquid without the addition of decomposition residue 
 remained unimpaired for several months. 
 
 Some of the black deposit being thrown down from a decomposing 
 sample was filtered from the liquid and added to a fresh portion of 
 clear liquid and then set away. The effect was in all respects the 
 same as described above, except that the chemical action was consid- 
 erably slower. In four days the liquid had become bright lemon 
 yellow ; in two weeks, brown ; and in five weeks had completely de- 
 composed. 
 
 Alkalies. — It has been long known that alkalies are favorable to 
 decomposition. This has been confirmed in our investigations using 
 sodium, potassium, and ammonium hydroxides. Ammonia was found 
 to be the most energetic. 
 
 Acids. — Sulfuric acid and hydrochloric acid even when used in 
 large amounts do not appear to affect the liquid seriously. Nitric acid, 
 however, has a very serious influence. 
 
 Sodium Cyanide. — The undesirable effect of sodium cyanide is 
 equal to or even greater than the alkalies mentioned above. 
 
 Soap. — Several varieties of soap were found to decompose the liquid 
 very rapidly. Doubtless this is due to the presence of alkali or to 
 hydrolysis of alkali salts. 
 
 Packing Materials. — Quite a variety of the more common packing 
 materials — pure rubber, red rubber, white rubber, leather, "garlock", 
 an asbestos packing, and an asphalt canvas packing — were experi- 
 mented with. So far as we were able to observe, there is nothing 
 dangerous about any of these ordinary materials used for packing so 
 far as the decomposing effect on hydrocyanic acid is concerned. 
 Rubber does not appear to affect the liquid, but the rubber itself is 
 sooner or later destroyed. 
 
 Metals. — Some metals are attacked by the acid. On the other 
 hand, some metals seem to act as catalytic agents and promote a rapid 
 decomposition of the acid. Others apparently have no effect what- 
 ever. The metals appearing to act upon the acid more energetically 
 are : lead, com,mercial tin, solder, cast iron, and steel. These metals 
 very clearly should be avoided in the construction of liquefying plants 
 and in delivery containers, atomizing machinery, fittings, etc. 
 
PHYSICAL AND CHEMICAL PROPERTIES OF HYDROCYANIC ACID 421 
 
 ACTION ON METALS 
 A series of experiments was made to test the action of liquid 
 hydrocyanic acid on various metals, the object being to obtain data 
 for the intelligent selection of materials for the construction of de- 
 livery containers, atomizing apparatus, condensers and other equip- 
 ment for use in connection with the new industry. 
 
 Small pieces of various metals, solid and plated, were first weighed 
 and then sealed in glass tubes containing a small quantity of liquid 
 hydrocyanic acid. The amount of liquid was regulated so that only 
 a part of the metals was exposed to the liquid while the remainder 
 was exposed to the vapors. These specimens have been under obser- 
 vation for four months and would all have furnished fairly complete 
 data on the action of the acid on the commoner metallic substances 
 except for the recent suspicion that the glass itself may have been 
 responsible for the decomposition of the liquid. 
 
 Our experiments have shown that certain kinds of glass under 
 some conditions appear to cause the decomposition of liquid hydro- 
 cyanic acid. So far as we are able to determine, boro-silicate glass 
 does not affect the liquid. The experiments are therefore being re- 
 peated, using this kind of glassware for the test containers. A large 
 variety of metals and various enamels and varnishes are also being 
 tested. The complete results of these experiments, however, will not 
 be available for the coming fumigating season. 
 
 Resistant Metals. — Notwithstanding the possible combined influence 
 of metal and glass upon liquid hydrocyanic acid, a few metals have 
 not been affected by four months' contact with prussic acid. Alumi- 
 num, block tin, and pure zinc apparently are not changed in the least 
 and the liquid in contact with them is as clear and colorless as when 
 first sealed up. The liquid on the brass, nickel, and silver has become 
 slightly yellow ; that on the copper is still good, but the copper has a 
 somewhat roughened appearance as if it had been slightly acted upon. 
 
 While pure zinc noted above is apparently quite resistant to the 
 action of prussic acid, a piece of plumbers' ordinary sheet zinc was 
 soon covered with a white coating and a considerable quantity of 
 white sediment was deposited in the liquid. The liquid itself remained 
 colorless and apparently unaffected throughout the experiment. 
 
 Delivery Druyns. — Judging from the experiments described above 
 and from a consideration of the cost and properties of the various 
 materials observed, aluminum is the most promising material for 
 the construction of delivery drums. Brass fittings appear to be per- 
 missible. 
 
422 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 SUMMARY 
 
 The ready acceptance, by fumigators, of liquid hydrocyanic acid 
 as a new convenience in citrus fumigation has resulted in a study of 
 the physical and chemical properties of the liquid. 
 
 Two test runs of the liquefying plant were made in order to estab- 
 lish a basis of settlement between plant and fumigator. The liquid 
 hydrocyanic acid recovered in the first test run was 80.1 per cent of 
 the greatest possible yield ; in the second, 76.3 per cent ; an average 
 of 78.2 per cent. 
 
 The average purity of the liquid obtained in the first run was 
 97.57 per cent ; in the second, 94.27 per cent. 
 
 The average purity of the liquid delivered during the past fumi- 
 gating season w^as above 95 per cent absolute hydrocyanic acid. 
 Material of 95 per cent or greater purity is considered of a satisfac- 
 tory grade. 
 
 As the plant was operated last season, the following is believed 
 to be a fair return per case of two hundred pounds of sodium cyanide : 
 
 1. A minimum of 85 pounds of absolute hydrocyanic acid; or 
 
 2. A minimum of 90 pounds of liquid testing not less than 95 per 
 cent purity. 
 
 As the necessary information is accumulated it is confidently an- 
 ticipated that the yield in tbe future will be equal to or even greater 
 than that now obtained from the portable generators in common use. 
 
 The weight basis for commercial transactions is strongly urged for 
 adoption in preference to the volume basis now in use. Deliveries 
 could be more easily checked up by weighing than by measuring, and 
 this is also less dangerous. Furthermore, the weight of the recovered 
 liquid will be the same at any temperature, while the corresponding 
 number of gallons will vary according to the temperature at which 
 it is measured. 
 
 A table has been prepared showing the weights and corresponding 
 volumes of various grades of commercial liquid and the quantities 
 thereof corresponding to various percentages of the maximum yield 
 (Table I). 
 
 It has been determined that the acid is miscible with water in all 
 proportions and will not stratify upon standing. 
 
 Hydrocyanic acid evaporates more rapidly than water from dilute 
 mixtures of the two. 
 
 Complete data have been obtained on the specific gravity of com- 
 mercial liquid hydrocyanic acid testing from 70 per cent to 100 per 
 
PHYSICAL AND CHEMICAL PROPERTIES OF HYDROCYANIC ACID 423 
 
 cent purity, and upon the extent of variation of hydrometer readings 
 as affected by temperature. These figures are presented in the form 
 of reference tables at the end of the bulletin. These tables make it 
 possible to determine the quality of a liquid in a moment's time by 
 the use of a hydrometer graduated either in specific gravity or Baume 
 degrees. 
 
 The accumulation of the data referred to above has made possible 
 the construction of a cyanometer, a hydrometer graduated directly in 
 percentages of hydrocyanic acid and provided with a simple table of 
 temperature corrections. 
 
 A method of analysis has been selected and shown to give concord- 
 ant results within two-tenths of 1 per cent. 
 
 The development of any color, usually yellow, or an odor of am- 
 monia may be taken as a warning of incipient decomposition of the 
 liquid. 
 
 Factors and materials favoring decomposition are : water in excess 
 of 5 per cent ; high temperatures ; residue from a decomposed liquid ; 
 all alkalies, nitric acid, sodium cyanide ; soap ; or contact with lead, 
 commercial tin, impure zinc, solder, cast iron, or steel. 
 
 The following metals were found to be highly resistant to the acid, 
 somewhat in the order named : aluminum, block tin, pure zinc, brass, 
 nickel, silver, and copper. 
 
 Aluminum is the most promising material for the construction of 
 delivery drums. Brass fittings are permissible. 
 
 REFERENCE TABLES 
 
 The following reference tables and their use in determining the 
 percentage of absolute hydrocyanic acid in commercial liquid hydro- 
 cyanic acid have been discussed under the heading ' ' Specific Gravity ' ' 
 in the section on physical properties. 
 
424 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 TABLE VI 
 
 For Use With Specific Gravity Hydrometer 
 Calibrated at 15° C 
 
 Observed Temperature ° C 
 
 Observed 
 
 
 
 
 
 
 
 
 
 
 Specific 
 
 22 
 
 21 
 
 20 
 
 19 
 
 18 
 
 17 
 
 16 
 
 15 
 
 14 
 
 Gravity 
 
 
 
 
 
 
 
 
 
 
 
 
 Corresponding Percent, l 
 
 Hydrocy; 
 
 anic Acid 
 
 
 .690 
 
 99.7 
 
 
 
 
 
 
 
 
 
 .692 
 
 99.1 
 
 99.5 
 
 99.9 
 
 
 
 
 
 
 
 .694 
 
 98.5 
 
 98.9 
 
 99.3 
 
 99.7 
 
 
 
 
 
 
 .696 
 
 97.9 
 
 98.3 
 
 98.7 
 
 99.1 
 
 99.5 
 
 99.9 
 
 
 
 
 .698 
 
 97.3 
 
 97.7 
 
 98.1 
 
 98.5 
 
 98.9 
 
 99.3 
 
 99.7 
 
 100 
 
 
 .700 
 
 96.7 
 
 97.1 
 
 97.5 
 
 97.9 
 
 98.3 
 
 98.7 
 
 99.1 
 
 99.6 
 
 100 
 
 .702 
 
 96.1 
 
 96.5 
 
 96.9 
 
 97.3 
 
 97.7 
 
 98.1 
 
 98.5 
 
 98.9 
 
 99.4 
 
 .704 
 
 95.5 
 
 95.9 
 
 96.3 
 
 96.7 
 
 97.1 
 
 97.5 
 
 97.9 
 
 98.4 
 
 98.8 
 
 .706 
 
 94.9 
 
 95.3 
 
 95.7 
 
 96.1 
 
 96.5 
 
 96.9 
 
 97.3 
 
 97.8 
 
 98.2 
 
 .708 
 
 94.3 
 
 94.7 
 
 95.1 
 
 95.5 
 
 95.9 
 
 96.3 
 
 96.7 
 
 97.1 
 
 97.6 
 
 .710 
 
 93.7 
 
 94.1 
 
 94.5 
 
 94.9 
 
 95.3 
 
 95.7 
 
 96.1 
 
 96.5 
 
 97.0 
 
 .712 
 
 93.1 
 
 93.5 
 
 93.9 
 
 94.3 
 
 94.7 
 
 95.1 
 
 95.5 
 
 95.9 
 
 96.4 
 
 .714 
 
 92.6 
 
 93.0 
 
 93.4 
 
 93.8 
 
 94.2 
 
 94.6 
 
 95.0 
 
 95.3 
 
 95.8 
 
 .716 
 
 92.0 
 
 92.4 
 
 92.8 
 
 93.2 
 
 93.6 
 
 94.0 
 
 94.4 
 
 94.7 
 
 95.2 
 
 .718 
 
 91.4 
 
 91.8 
 
 92.2 
 
 92.6 
 
 93.0 
 
 93.4 
 
 93.8 
 
 94.1 
 
 94.6 
 
 .720 
 
 90.8 
 
 91.2 
 
 91.6 
 
 92.0 
 
 92.4 
 
 92.8 
 
 93.2 
 
 93.6 
 
 94.0 
 
 .722 
 
 90.2 
 
 90.6 
 
 91.0 
 
 91.4 
 
 91.8 
 
 92.2 
 
 92.6 
 
 93.0 
 
 93.4 
 
 .724 
 
 89.6 
 
 90.0 
 
 90.4 
 
 90.8 
 
 91.2 
 
 91.6 
 
 92.0 
 
 92.4 
 
 92.8 
 
 .726 
 
 89.0 
 
 89.4 
 
 89.8 
 
 90.2 
 
 90.6 
 
 91.0 
 
 91.4 
 
 91.8 
 
 92.2 
 
 .728 
 
 88.5 
 
 88.9 
 
 89.3 
 
 89.7 
 
 90.1 
 
 90.5 
 
 90.9 
 
 91.2 
 
 91.6 
 
 .730 
 
 87.9 
 
 88.3 
 
 88.7 
 
 89.1 
 
 89.5 
 
 89.9 
 
 90.3 
 
 90.6 
 
 91.0 
 
 .732 
 
 87.3 
 
 87.7 
 
 88.1 
 
 88.5 
 
 88.9 
 
 89.3 
 
 89.7 
 
 90.0 
 
 90.4 
 
 .734 
 
 86.7 
 
 87.1 
 
 87.5 
 
 87.9 
 
 88.3 
 
 88.7 
 
 89.1 
 
 89.4 
 
 89.8 
 
 .736 
 
 86.2 
 
 86.5 
 
 87.0 
 
 87.4 
 
 87.8 
 
 88.2 
 
 88.6 
 
 88.8 
 
 89.2 
 
 .738 
 
 85.6 
 
 86.0 
 
 86.4 
 
 86.8 
 
 87.2 
 
 87.5 
 
 87.9 
 
 88.2 
 
 88.6 
 
 .740 
 
 85.0 
 
 85.4 
 
 85.8 
 
 86.2 
 
 86.6 
 
 86.9 
 
 87.3 
 
 87.6 
 
 88.0 
 
 .742 
 
 84.4 
 
 84.8 
 
 85.2 
 
 85.6 
 
 86.0 
 
 86.3 
 
 86.7 
 
 87.0 
 
 87.4 
 
 .744 
 
 83.8 
 
 84.2 
 
 84.6 
 
 85.0 
 
 85.4 
 
 85.7 
 
 86.1 
 
 86.4 
 
 86.8 
 
 .746 
 
 83.3 
 
 83.7 
 
 84.1 
 
 84.5 
 
 84.8 
 
 85.1 
 
 85.5 
 
 85.8 
 
 86.2 
 
 .748 
 
 82.7 
 
 83.1 
 
 83.5 
 
 83.9 
 
 84.2 
 
 84.5 
 
 84.9 
 
 85.2 
 
 85.6 
 
 .750 
 
 82.1 
 
 82.5 
 
 82.9 
 
 83.3 
 
 83.6 
 
 83.9 
 
 84.3 
 
 84.6 
 
 85.0 
 
 . 752 
 
 81.6 
 
 82.0 
 
 82.4 
 
 82.7 
 
 83.0 
 
 83.3 
 
 83.6 
 
 84.0 
 
 84.4 
 
 .754 
 
 81.0 
 
 81.4 
 
 81.8 
 
 82.1 
 
 82.4 
 
 82.7 
 
 83.1 
 
 83.5 
 
 83.8 
 
 .756 
 
 80.4 
 
 80.8 
 
 81.2 
 
 81.5 
 
 81.8 
 
 82.1 
 
 82.5 
 
 82.9 
 
 83.2 
 
PHYSICAL AND CHEMICAL PROPERTIES OF HYDROCYANIC ACID 
 
 425 
 
 Observed 
 Specific 
 Gravity 
 
 .690 
 .692 
 .694 
 .69) 
 .698 
 
 .700 
 .702 
 .704 
 .706 
 .708 
 
 .710 
 .712 
 .714 
 .716 
 
 .718 
 
 .720 
 
 ,722 
 
 .724 
 
 726 
 
 .728 
 
 ,730 
 ,732 
 ,734 
 ,736 
 
 ,738 
 
 ,740 
 ,742 
 
 ,744 
 ,746 
 ,748 
 
 .750 
 ,752 
 .754 
 ,756 
 
 TABLE VI (Continued) 
 For Use With Specific Gravity Hydrometer 
 Calibrated at 15° C 
 
 13 
 
 12 
 
 Observed Temperature ° C 
 11 10 9 8 7 
 
 Corresponding Percent. Hydrocyanic Acid 
 
 6 
 
 99.8 
 
 ........ 
 
 
 
 
 
 
 
 
 99.2 
 
 99.6 
 
 100 
 
 
 
 
 
 
 
 98.6 
 
 99.0 
 
 99.4 
 
 99.8 
 
 
 
 
 
 
 98.0 
 
 98.4 
 
 98.8 
 
 99.2 
 
 99.6 
 
 100 
 
 
 
 
 
 97.4 
 
 97.8 
 
 98.2 
 
 98.6 
 
 99.0 
 
 99.4 
 
 99.9 
 
 
 
 96.8 
 
 97.2 
 
 97.6 
 
 98.0 
 
 98.4 
 
 98.8 
 
 99.3 
 
 99.7 
 
 
 96.2 
 
 96.6 
 
 97.0 
 
 97.4 
 
 97.8 
 
 98.2 
 
 98.7 
 
 99.1 
 
 99.6 
 
 95.6 
 
 96.0 
 
 96.4 
 
 96.7 
 
 97.2 
 
 97.6 
 
 98.1 
 
 98.5 
 
 99.0 
 
 95.0 
 
 95.4 
 
 95.8 
 
 96.1 
 
 96.6 
 
 97.0 
 
 97.5 
 
 97.9 
 
 98.4 
 
 94.4 
 
 94.8 
 
 95.2 
 
 95.5 
 
 96.0 
 
 96.4 
 
 96.9 
 
 97.3 
 
 97.8 
 
 93.8 
 
 94.2 
 
 94.5 
 
 94.9 
 
 95.3 
 
 95.8 
 
 96.2 
 
 96.6 
 
 97.1 
 
 93.2 
 
 93.6 
 
 93.9 
 
 94.3 
 
 94.7 
 
 95.1 
 
 95.6 
 
 96.0 
 
 96.5 
 
 92.6 
 
 93.0 
 
 93.3 
 
 93.7 
 
 94.1 
 
 94.5 
 
 95.0 
 
 95.4 
 
 95.9 
 
 92.0 
 
 92.4 
 
 92.8 
 
 93.1 
 
 93.5 
 
 93.9 
 
 94.3 
 
 94.7 
 
 95.3 
 
 91.4 
 
 91.8 
 
 92.2 
 
 92.5 
 
 92.9 
 
 93.3 
 
 93.7 
 
 94.1 
 
 94.7 
 
 90.8 
 
 91.2 
 
 91.6 
 
 91.9 
 
 92.3 
 
 92.7 
 
 93.1 
 
 93.5 
 
 94.0 
 
 90.2 
 
 90.6 
 
 91.0 
 
 91.3 
 
 91.7 
 
 92.1 
 
 92.5 
 
 92.9 
 
 93.4 
 
 89.6 
 
 90.0 
 
 90.4 
 
 90.7 
 
 91.1 
 
 91.5 
 
 91.9 
 
 92.3 
 
 92.8 
 
 89.0 
 
 89.4 
 
 89.8 
 
 90.1 
 
 90.5 
 
 90.9 
 
 91.3 
 
 91.7 
 
 92.2 
 
 88.4 
 
 88.8 
 
 89.2 
 
 89.5 
 
 89.9 
 
 90.3 
 
 90.7 
 
 91.1 
 
 91.6 
 
 87.8 
 
 88.2 
 
 88.6 
 
 88.9 
 
 89.3 
 
 89.7 
 
 90.1 
 
 90.5 
 
 91.0 
 
 87.2 
 
 87.6 
 
 88.0 
 
 88.3 
 
 88.7 
 
 89.1 
 
 89.5 
 
 89.9 
 
 90.4 
 
 86.6 
 
 87.0 
 
 87.4 
 
 87.7 
 
 88.1 
 
 88.5 
 
 88.9 
 
 89.3 
 
 89.8 
 
 86.0 
 
 86.4 
 
 86.8 
 
 87.1 
 
 87.5 
 
 87.9 
 
 88.3 
 
 88.7 
 
 89.1 
 
 85.4 
 
 85.8 
 
 86. 2 
 
 86.5 
 
 86.9 
 
 87.3 
 
 87.7 
 
 88.1 
 
 88.5 
 
 84.8 
 
 85.2 
 
 85.6 
 
 85.9 
 
 86.3 
 
 86.7 
 
 87.1 
 
 87.5 
 
 87.9 
 
 84.2 
 
 84.6 
 
 85.0 
 
 85.3 
 
 85.7 
 
 86.1 
 
 86.5 
 
 86.9 
 
 87.3 
 
 83.6 
 
 84.0 
 
 84.4 
 
 84.7 
 
 85.1 
 
 85.5 
 
 85.9 
 
 86.3 
 
 86.7 
 
426 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 TABLE VII 
 
 For Use With Baume Hydrometer 
 
 Calibrated at 60°F. 
 
 Observed Temperature °F. 
 
 Observed 
 
 
 
 
 
 
 
 
 
 
 
 
 Degrees 
 
 70 
 
 69 
 
 68 
 
 67 
 
 66 
 
 65 
 
 64 
 
 63 
 
 62 
 
 61 
 
 60 
 
 Baume. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Corresponding Percent. ; 
 
 Hydrocyanic Acid 
 
 
 
 72.5 
 
 99.7 
 
 100 
 
 
 
 
 
 
 
 
 
 
 72.0 
 
 99.1 
 
 99.3 
 
 99.5 
 
 99.7 
 
 99.9 
 
 
 
 
 
 
 
 71.5 
 
 98.6 
 
 98.8 
 
 99.0 
 
 99.2 
 
 99.4 
 
 99.7 
 
 100 
 
 
 
 
 
 
 71.0 
 
 98.1 
 
 98.3 
 
 98.6 
 
 98.8 
 
 99.0 
 
 99.2 
 
 99.4 
 
 99.6 
 
 99.8 
 
 100 
 
 , 
 
 70.5 
 
 97.6 
 
 97.8 
 
 98.0 
 
 98.2 
 
 98.4 
 
 98.6 
 
 98.8 
 
 99.1 
 
 99.3 
 
 99.5 
 
 99.7 
 
 70.0 
 
 97.1 
 
 97.3 
 
 97.5 
 
 97.7 
 
 98.0 
 
 98.2 
 
 98.4 
 
 98.7 
 
 98.9 
 
 99.1 
 
 99.3 
 
 69.5 
 
 96.6 
 
 96.8 
 
 97.0 
 
 97.2 
 
 97.4 
 
 97.6 
 
 97.8 
 
 98.0 
 
 98.2 
 
 98.4 
 
 98.7 
 
 69.0 
 
 96.1 
 
 96.3 
 
 96.5 
 
 96.7 
 
 97.0 
 
 97.2 
 
 97.4 
 
 07.6 
 
 97.8 
 
 98.1 
 
 98.3 
 
 68.5 
 
 95.5 
 
 95.7 
 
 95.9 
 
 96.1 
 
 96.4 
 
 96.6 
 
 96.9 
 
 97.1 
 
 97.3 
 
 97.6 
 
 97.8 
 
 68.0 
 
 95.0 
 
 95.2 
 
 95.4 
 
 95.6 
 
 95.9 
 
 96.1 
 
 96.3 
 
 96.5 
 
 96.8 
 
 97.0 
 
 97.2 
 
 67.5 
 
 94.4 
 
 94.6 
 
 94.8 
 
 95.0 
 
 95.3 
 
 95.5 
 
 95.7 
 
 95.9 
 
 96.1 
 
 96.4 
 
 96.6 
 
 67.0 
 
 93.9 
 
 94.1 
 
 94.3 
 
 94.5 
 
 94.8 
 
 95.0 
 
 95.2 
 
 95.4 
 
 95.6 
 
 95.9 
 
 96.1 
 
 66.5 
 
 93.4 
 
 93.6 
 
 93.8 
 
 94.0 
 
 94.3 
 
 94.5 
 
 94.7 
 
 94.9 
 
 95.2 
 
 95.4 
 
 95.6 
 
 66.0 
 
 92.9 
 
 93.1 
 
 93.3 
 
 93.5 
 
 93.7 
 
 94.0 
 
 94.2 
 
 94.4 
 
 94.6 
 
 94.9 
 
 95.1 
 
 65.5 
 
 92.4 
 
 92.6 
 
 92.8 
 
 93.0 
 
 93.2 
 
 93.5 
 
 93.7 
 
 93.9 
 
 94.1 
 
 94.3 
 
 94.5 
 
 65.0 
 
 91.8 
 
 92.0 
 
 92.2 
 
 92.4 
 
 92.6 
 
 92.8 
 
 93.1 
 
 93.3 
 
 93.5 
 
 93.7 
 
 93.9 
 
 64.5 
 
 91.2 
 
 91.4 
 
 91.6 
 
 91.8 
 
 92.1 
 
 92.3 
 
 92.5 
 
 92.7 
 
 92.9 
 
 93.2 
 
 93.4 
 
 64.0 
 
 90.7 
 
 90.9 
 
 91.1 
 
 91.3 
 
 91.6 
 
 91.8 
 
 92.0 
 
 92.2 
 
 92.4 
 
 92.7 
 
 92.9 
 
 63.5 
 
 90.1 
 
 90.3 
 
 90.5 
 
 90.7 
 
 90.9 
 
 91.2 
 
 91.4 
 
 91.6 
 
 91.8 
 
 92.1 
 
 92.3 
 
 63.0 
 
 89.6 
 
 89.8 
 
 90.0 
 
 90.2 
 
 90.5 
 
 90.7 
 
 90.9 
 
 91.1 
 
 91.4 
 
 91.6 
 
 91.8 
 
 62.5 
 
 89.1 
 
 89.3 
 
 89.5 
 
 89.7 
 
 89.9 
 
 90.2 
 
 90.4 
 
 90.6 
 
 90.8 
 
 91.0 
 
 91.2 
 
 62.0 
 
 88.5 
 
 88.7 
 
 88.9 
 
 89.1 
 
 89.3 
 
 89.6 
 
 89.8 
 
 90.0 
 
 90.2 
 
 90.4 
 
 90.6 
 
 61.5 
 
 88.0 
 
 88.2 
 
 88.4 
 
 88.6 
 
 88.8 
 
 89.0 
 
 89.3 
 
 89.5 
 
 89.7 
 
 89.9 
 
 90.1 
 
 61.0 
 
 87.3 
 
 87.5 
 
 87.7 
 
 87.9 
 
 88.1 
 
 88.3 
 
 88.6 
 
 88.8 
 
 89.0 
 
 89.2 
 
 89.4 
 
 60.5 
 
 86.8 
 
 87.0 
 
 87.2 
 
 87.4 
 
 87.6 
 
 87.8 
 
 88.0 
 
 88.3 
 
 88.5 
 
 88.7 
 
 88.9 
 
 60.0 
 
 86.3 
 
 86.5 
 
 86.7 
 
 86.9 
 
 87.1 
 
 87.4 
 
 87.6 
 
 87.8 
 
 88.0 
 
 88.2 
 
 88.4 
 
 59.5 
 
 85.8 
 
 86.0 
 
 86.2 
 
 86.4 
 
 86.6 
 
 86.8 
 
 87.0 
 
 87.2 
 
 87.4 
 
 87.6 
 
 87.8 
 
 59.0 
 
 85.2 
 
 85.4 
 
 85.6 
 
 85.8 
 
 86.0 
 
 86.2 
 
 86.4 
 
 86.6 
 
 86.8 
 
 87.0 
 
 87.2 
 
 58.5 
 
 84.6 
 
 84.8 
 
 85.0 
 
 85.2 
 
 85.4 
 
 85.6 
 
 85.8 
 
 86.0 
 
 86.2 
 
 86.4 
 
 86.6 
 
 58.0 
 
 84.0 
 
 84.2 
 
 84.4 
 
 84.6 
 
 84.8 
 
 85.0 
 
 85.2 
 
 85.4 
 
 85.6 
 
 85.8 
 
 86.0 
 
 57.5 
 
 83.5 
 
 83.7 
 
 83.9 
 
 84.1 
 
 84.3 
 
 84.5 
 
 84.7 
 
 84.9 
 
 85.1 
 
 85.3 
 
 85.5 
 
 57.0 
 
 82.9 
 
 83.1 
 
 83.3 
 
 83.5 
 
 83.7 
 
 83.9 
 
 84.1 
 
 84.3 
 
 84.5 
 
 84.7 
 
 84.9 
 
 56.0 
 
 82.3 
 
 82.5 
 
 82.7 
 
 82.9 
 
 83.1 
 
 83.3 
 
 83.5 
 
 83.7 
 
 83.9 
 
 84.1 
 
 84.3 
 
PHYSICAL AND CHEMICAL PROPERTIES OF HYDROCYANIC ACID 
 
 427 
 
 TABLE VII (Continued) 
 
 For Use With Baume Hydrometer 
 Calibrated at 60°F. 
 
 Observed Temperature °F. 
 
 Observed 
 
 
 
 
 
 
 
 
 
 
 
 Degrees 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 Baume 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Corresponding 
 
 ; Percent. Hydrocyanic Acid 
 
 
 
 72.5 
 
 
 
 
 
 
 
 
 
 
 
 72.0 
 
 
 
 
 
 
 
 
 
 
 
 71.5 
 
 
 
 
 
 
 
 
 
 
 
 71.0 
 
 
 
 
 
 
 
 
 
 
 
 70.5 
 
 100 
 
 
 
 
 
 
 
 
 
 
 70.0 
 
 99.6 
 
 99.8 
 
 100 
 
 
 
 
 
 
 
 
 69.5 
 
 99.0 
 
 99.2 
 
 99.4 
 
 99.6 
 
 99.8 
 
 100 
 
 
 
 
 
 69.0 
 
 98.5 
 
 98.7 
 
 98.9 
 
 99.1 
 
 99.3 
 
 99.5 
 
 99.8 
 
 100 
 
 
 
 68.5 
 
 98.0 
 
 98.2 
 
 98.4 
 
 98.6 
 
 98.8 
 
 99.0 
 
 99.3 
 
 99.5 
 
 99.7 
 
 100 
 
 68.0 
 
 97.4 
 
 97.6 
 
 97.8 
 
 98.1 
 
 98.3 
 
 98.5 
 
 98.8 
 
 99.0 
 
 99.2 
 
 99.5 
 
 67.5 
 
 96.9 
 
 97.1 
 
 97.3 
 
 97.5 
 
 97.8 
 
 98.0 
 
 98.2 
 
 98.4 
 
 98.6 
 
 98.9 
 
 67.0 
 
 96.3 
 
 96.5 
 
 96.8 
 
 97.0 
 
 97.2 
 
 97.5 
 
 97.7 
 
 97.9 
 
 98.1 
 
 98.4 
 
 66.5 
 
 95.8 
 
 96.0 
 
 96.3 
 
 96.5 
 
 96.7 
 
 96.9 
 
 97.1 
 
 97.4 
 
 97.6 
 
 97.8 
 
 66.0 
 
 95.3 
 
 95.5 
 
 95.7 
 
 96.0 
 
 96.2 
 
 96.4 
 
 96.6 
 
 96.9 
 
 97.1 
 
 97.3 
 
 65.5 
 
 94.7 
 
 95.0 
 
 95.2 
 
 95.4 
 
 95.6 
 
 95.9 
 
 96.1 
 
 96.3 
 
 96.5 
 
 96.7 
 
 65.0 
 
 94.1 
 
 94.4 
 
 94.6 
 
 94.8 
 
 95.0 
 
 95.3 
 
 95.5 
 
 95.7 
 
 95.9 
 
 96.1 
 
 64.5 
 
 93.6 
 
 93.8 
 
 94.0 
 
 94.3 
 
 94.5 
 
 94.7 
 
 94.9 
 
 95.1 
 
 95.3 
 
 95.5 
 
 64.0 
 
 93.1 
 
 93.3 
 
 93.5 
 
 93.7 
 
 94.0 
 
 94.2 
 
 94.4 
 
 94.6 
 
 94.8 
 
 95.0 
 
 63.5 
 
 92.5 
 
 92.7 
 
 92.9 
 
 93.1 
 
 93.4 
 
 93.6 
 
 93.8 
 
 94.0 
 
 94.2 
 
 94.4 
 
 63.0 
 
 92.0 
 
 92.2 
 
 92.4 
 
 92.6 
 
 92.9 
 
 93.1 
 
 93.3 
 
 93.5 
 
 93.7 
 
 93.9 
 
 62.5 
 
 91.4 
 
 91.7 
 
 91.9 
 
 92.1 
 
 92.3 
 
 92.5 
 
 92.7 
 
 92.9 
 
 93.1 
 
 93.3 
 
 62.0 
 
 90.8 
 
 91.0 
 
 91.3 
 
 91.5 
 
 91.7 
 
 91.9 
 
 92.1 
 
 92.3 
 
 92.5 
 
 92.7 
 
 61.5 
 
 90.3 
 
 90.5 
 
 90.7 
 
 90.9 
 
 91.1 
 
 91.3 
 
 91.5 
 
 91.8 
 
 92.0 
 
 92.2 
 
 61.0 
 
 89.6 
 
 89.8 
 
 90.0 
 
 90.4 
 
 90.5 
 
 90.7 
 
 90.9 
 
 91.2 
 
 91.4 
 
 91.6 
 
 60.5 
 
 89.1 
 
 89.3 
 
 89.5 
 
 89.8 
 
 90.0 
 
 90.2 
 
 90.4 
 
 90.6 
 
 90.8 
 
 91.0 
 
 60.0 
 
 88.6 
 
 88.8 
 
 89.0 
 
 89.3 
 
 89.5 
 
 89.7 
 
 89.9 
 
 90.1 
 
 90.3 
 
 90.5 
 
 59.5 
 
 88.0 
 
 88.3 
 
 88.5 
 
 88.7 
 
 88.9 
 
 89.1 
 
 89.3 
 
 89.5 
 
 89.7 
 
 89.9 
 
 59.0 
 
 87.4 
 
 87.6 
 
 87.9 
 
 88.1 
 
 88.3 
 
 88.5 
 
 88.7 
 
 88.9 
 
 89.1 
 
 89.3 
 
 58.5 
 
 86.8 
 
 87.0 
 
 87.3 
 
 87.5 
 
 87.7 
 
 87.9 
 
 88.1 
 
 88.3 
 
 88.5 
 
 88.7 
 
 58.0 
 
 86.2 
 
 86.5 
 
 86.7 
 
 86.9 
 
 87.1 
 
 87.3 
 
 87.5 
 
 87.7 
 
 87.9 
 
 88.1 
 
 57.5 
 
 85.7 
 
 85.9 
 
 86.1 
 
 86.3 
 
 86.5 
 
 86.7 
 
 86.9 
 
 87.1 
 
 87.3 
 
 87.5 
 
 57.0 
 
 85.1 
 
 85.3 
 
 85.5 
 
 85.7 
 
 85.9 
 
 86.1 
 
 86.3 
 
 86.5 
 
 86.7 
 
 86.9 
 
 56.5 
 
 84.5 
 
 84.7 
 
 84.9 
 
 85.1 
 
 85.3 
 
 85.5 
 
 85.7 
 
 85.9 
 
 86.1 
 
 86.3 
 
428 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 TABLE VII {Concluded) 
 
 For Use With Baume Hydrometer 
 Calibrated at 60°F. 
 
 Observed Temperature °F. 
 
 Observed 
 
 
 
 
 
 
 
 
 
 
 
 Degrees 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 40 
 
 Baume 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Corresponding 
 
 ; Percent. Hydrocyanic 
 
 Acid 
 
 
 
 72.-5 
 
 
 
 
 
 
 
 
 
 
 
 72.0 
 
 
 
 
 
 
 
 
 
 
 
 71.5 
 
 
 
 
 
 
 
 
 
 
 
 71.0 
 
 
 
 
 
 
 
 
 
 
 
 70.5 
 
 
 
 
 
 
 
 
 
 
 
 70.0 
 
 
 
 
 
 
 
 
 
 
 
 69.5 
 
 
 
 
 
 
 
 
 
 
 
 69.0 
 
 
 
 
 
 
 
 
 
 
 
 68.5 
 
 
 
 
 
 
 
 
 
 
 
 68.0 
 
 99.7 
 
 10) 
 
 
 
 
 
 
 
 
 
 67.5 
 
 99.1 
 
 99.4 
 
 99.6 
 
 99.9 
 
 
 
 
 
 
 
 67.0 
 
 98.6 
 
 98.8 
 
 99.1 
 
 99.3 
 
 99.6 
 
 99.8 
 
 100 
 
 
 
 
 66.5 
 
 98.0 
 
 98.3 
 
 98.5 
 
 98.7 
 
 99.0 
 
 99.2 
 
 99.4 
 
 99.6 
 
 99.8 
 
 100 
 
 66.0 
 
 97.5 
 
 97.8 
 
 98.0 
 
 98.3 
 
 98.5 
 
 98.7 
 
 98.9 
 
 99.1 
 
 99.3 
 
 99.5 
 
 65.5 
 
 97.0 
 
 97.2 
 
 97.5 
 
 97.7 
 
 98.0 
 
 98.2 
 
 98.4 
 
 98.6 
 
 98.9 
 
 99.1 
 
 65.0 
 
 96.4 
 
 96.6 
 
 96.9 
 
 97.2 
 
 97.4 
 
 97.7 
 
 97.9 
 
 98.1 
 
 98.4 
 
 98.6 
 
 64.5 
 
 95.8 
 
 96.0 
 
 96.3 
 
 96.6 
 
 96.8 
 
 97.1 
 
 97.3 
 
 97.6 
 
 97.8 
 
 98.1 
 
 64.0 
 
 95.3 
 
 95.5 
 
 95.8 
 
 96.0 
 
 96.3 
 
 96.5 
 
 96.8 
 
 97.0 
 
 97.2 
 
 97.5 
 
 63.5 
 
 94.7 
 
 94.9 
 
 95.2 
 
 95.5 
 
 95.7 
 
 95.9 
 
 96.2 
 
 96.4 
 
 96.6 
 
 96.9 
 
 63.0 
 
 94.2 
 
 94.4 
 
 94.7 
 
 94.9 
 
 95.1 
 
 95.4 
 
 95.6 
 
 95.9 
 
 96.1 
 
 96.3 
 
 62.5 
 
 93.6 
 
 93.8 
 
 94.1 
 
 94.3 
 
 94.6 
 
 94.8 
 
 95.1 
 
 95.3 
 
 95.5 
 
 95.7 
 
 62.0 
 
 93.0 
 
 93.2 
 
 93.5 
 
 93.7 
 
 94.0 
 
 94.2 
 
 94.5 
 
 94.7 
 
 94.9 
 
 95.1 
 
 61.5 
 
 92.4 
 
 92.7 
 
 92.9 
 
 93.2 
 
 93.4 
 
 93.6 
 
 93.9 
 
 94.1 
 
 94.4 
 
 94.6 
 
 61.0 
 
 91.8 
 
 92.1 
 
 92.3 
 
 92.6 
 
 92.8 
 
 93.0 
 
 93.3 
 
 93.5 
 
 93.7 
 
 93.9 1 
 
 60.5 
 
 91.3 
 
 91.5 
 
 91.7 
 
 92.0 
 
 92.2 
 
 92.4 
 
 92.7 
 
 92.9 
 
 93.1 
 
 93.3 ■' 
 
 60.0 
 
 90.8 
 
 91.0 
 
 91.2 
 
 91.5 
 
 91.7 
 
 91.9 
 
 92.1 
 
 92.4 
 
 92.6 
 
 92.8 
 
 59.5 
 
 90.2 
 
 90.4 
 
 90.6 
 
 90.9 
 
 91.1 
 
 91.3 
 
 91.5 
 
 91.8 
 
 92 
 
 92.2 
 
 59.0 
 
 89.6 
 
 89.8 
 
 90.0 
 
 90.3 
 
 90.5 
 
 90.7 
 
 90.9 
 
 91.2 
 
 91.4 
 
 91.6 
 
 58.5 
 
 89.0 
 
 89.2 
 
 89.4 
 
 89.7 
 
 89.9 
 
 90.1 
 
 90.3 
 
 90.6 
 
 90.8 
 
 91.0 
 
 58.0 
 
 88.4 
 
 88.6 
 
 88.8 
 
 89.1 
 
 89.3 
 
 89.5 
 
 89.7 
 
 90.0 
 
 90.2 
 
 90.4 
 
 57.5 
 
 87.8 
 
 88.0 
 
 88.2 
 
 88.4 
 
 88.7 
 
 88.9 
 
 89.1 
 
 89.4 
 
 89.6 
 
 89.8 
 
 57.0 
 
 87.2 
 
 87.4 
 
 87.6 
 
 87.8 
 
 88.0 
 
 88.3 
 
 88.5 
 
 88.7 
 
 88.9 
 
 89.1 
 
 56.5 
 
 86.6 
 
 80.8 
 
 87.0 
 
 87.2 
 
 87.4 
 
 87.0 
 
 87.8 
 
 88.0 
 
 88.2 
 
 88.4 
 
STATION PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION 
 
 No. 
 
 230. 
 242. 
 250. 
 251. 
 
 252. 
 25i. 
 
 255. 
 257. 
 261. 
 
 262. 
 
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 267. 
 268. 
 270. 
 
 271. 
 272. 
 273. 
 
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 277. 
 
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 115. 
 117. 
 
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 148. 
 151. 
 152. 
 
 153. 
 
 154. 
 
 155. 
 156. 
 157. 
 158. 
 160. 
 162. 
 
 164. 
 165. 
 
 166. 
 
 Enological Investigations. 
 
 Humus in California Soils. 
 
 The Loquat. 
 
 Utilization of the Nitrogen and Organic 
 Matter in Septic and Imhoflf Tank 
 Sludges. 
 
 Deterioration of Lumber. 
 
 Irrigation and Soil Conditions in the 
 Sieira Nevada Foothills, California. 
 
 The Citricola Scale. 
 
 New Dosage Tables. 
 
 Melaxuma of the Walnut, "Juglans 
 regia." 
 
 Citrus Diseases of Florida and Cuba 
 Compared vy^ith Those of California. 
 
 Size Grades for Ripe Olives. 
 
 The Calibration of the Leakage Meter. 
 
 A Spotting of Citrus Fruits Due to the 
 Action of Oil Liberated from the Rind. 
 
 Experiments with Stocks for Citrus. 
 
 Growing and Grafting Olive Seedlings. 
 
 A Comparison of Annual Cropping, Bi- 
 ennial Cropping, and Green Manures 
 on the Yield of Wheat. 
 
 Feeding Dairy Calves in California. 
 
 Commercial Fertilizers. 
 
 Preliminary Report on Kearney Vincr 
 yard Experimental Drain. 
 
 The Common Honey Bee as an Agent 
 in Prune Pollination. 
 
 The Cultivation of Belladonna in Cali- 
 fornia. 
 
 The Pomegranate. 
 
 Sudan Grass. 
 
 BULLETINS 
 
 No. 
 
 278. 
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 286. 
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 292. 
 
 293. 
 296. 
 297. 
 298. 
 299. 
 
 300. 
 801. 
 
 302. 
 
 303. 
 304. 
 
 305. 
 
 CIRCULARS 
 
 No. 
 
 167. 
 
 168. 
 
 Increasing the Duty of Water. 
 
 Grafting Vinifera Vineyards. 
 
 The Selection and Cost of a Small 
 
 Pumping Plant. 169. 
 
 Alfalfa Silage for Fattening Steers. 170. 
 Spraying for the Grape Leaf Hopper 
 
 House Fumigation. 172. 
 
 Insecticide Formulas. 173 
 The Control of Citrus Insects. 
 
 Spraying for Control of Walnut Aphis. 174. 
 
 County Farm Adviser. 175. 
 Official Tests of Dairy Cows. 
 
 Melilotus Indica. 176. 
 Wood Decay in Orchard Trees. 
 
 The Silo in California Agriculture. 177. 
 
 The Generation of Hydrocyanic Acid 179. 
 
 Gas in Fumigation by Portable Ma- 
 chines. 181. 
 Thf Practical Application of Improved 
 
 Methods of Fermentation in Califor- 182. 
 
 nia Wineries during 1913 and 1914. 
 
 Practical and Inexpensive Poultry Ap- 183. 
 
 pliances. 184. 
 
 Control of Grasshoppers in Imperial 186. 
 
 Valley. 187. 
 
 Oidium or Powdery Mildew of the Vine. 188. 
 
 Tomato Growing in California. 189. 
 
 "Lungworms." 190. 
 
 Feeding and Management of Hogs. 191 
 
 Some Observations on the Bulk Hand- 193. 
 
 ling of Grain in California. 195. 
 Announcement of the California State 
 
 Dairy Cow Competition, 1916-18. 197. 
 Irrigation Practice in Growing Small 
 
 Fruits in California. 198. 
 
 Bovine Tuberculosis. 200. 
 How to operate an Incubator. 
 
 Control of the Penr Scab. 201. 
 
 Home and Farm Canning. 202. 
 Ijpttuce Growing in California. 
 
 White Diarrhoea and Coccidiosis of 203. 
 
 Chicks. 204, 
 Small Fruit Culture in California. 
 
 Fundamentals of Sugar Beet Culture 205. 
 
 under California Conditions. 206. 
 
 The County Farm Bureau. 207. 
 
 Grain Sorghums. 
 
 Irrigation of Rice in California. 
 
 Irrigation of Alfalfa in the Sacramento 
 Valley. 
 
 Control of the Pocket Gopher in Cali- 
 fornia. 
 
 Trials with California Silage Crops for 
 Dairy Cows. 
 
 The Olive Insects of California. 
 
 Irrigation of Alfalfa in Imperial Valley. 
 
 The Milch Goat in California. 
 
 Commercial Fertilizers. 
 
 Potash from Tule and the Fertilizer 
 Value of Certain Marsh Plants. 
 
 The June Drop of Washington Navel 
 Oranges. 
 
 Green Manure Crops in Southern Cali- 
 fornia. 
 
 Sweet Sorghums for Forage. 
 
 Topping and Pinching Vines. 
 
 The Almond in California. 
 
 Seedless Raisin Grapes. 
 
 The Use of Lumber on California 
 Farms. 
 
 Commercial Fertilizers. 
 
 California State Dairy Cow Competi- 
 tion, 1916-18. 
 
 Control of Ground Squirrels by the 
 Fumigation Method. 
 
 Grape Syrup. 
 
 A Study of the Effects of Freezes on 
 Citrus in California. 
 
 The Influence of Barley on the Milk 
 Secretions of Cows. 
 
 Feeding Stuffs of Minor Importance. 
 Spraying for the Control of Wild Morn- 
 
 ing-Glory within the Fog Belt. 
 The 1918 Grain Crop. 
 Fertilizing California Soils for the 
 
 1918 Crop. 
 Wheat Culture. 
 The Construction of the Wood-Hoop 
 
 Silo. 
 Farm Drainage Methods. 
 Progress Report on the Marketing and 
 
 Distribution of Milk. 
 Hog Cholera Prevention and the 
 
 Serum Treatment. 
 Grain Sorghums. 
 Factors of Importance in Producing 
 
 Milk of Low Bacterial Count. 
 Control of the California Ground 
 
 Squirrel. 
 Extending the Area of Irrigated Wheat 
 
 in California for 1918. 
 Infectious Abortion in Cows. 
 A Flock of Sheep on the Farm. 
 Poultry on the Farm. 
 Utilizing the Sorghums. 
 Lambing Sheds. 
 Winter Forage Crops. 
 Agriculture Clubs in California. 
 Pruning the Seedless Grapes. 
 A Study of Farm Labor in California. 
 Revised Compatibility Chart of Insecti- 
 cides and Fungicides. 
 Suggestions for Increasing Egg Pro- 
 duction in a Time of High-Feed Prices. 
 Syrup from Sweet Sorghum. 
 Growing the Fall or Second Crop of 
 
 Potatoes in California. 
 Helpful Hints to Hog Raisers. 
 County Organization for Rural Fire 
 
 Control. 
 Peat as a Manure Substitute. 
 Handbook of Plant Diseases and Pest 
 
 Control. 
 Blackleg. 
 Jack Cheese. 
 Neufchatel Cheese.