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Laa diagrammaa auivanta illustrant la mtthoda. - 1 2 3 1 2 3 4 5 6 mxocan mouiTioN mr cnart (ANSI ond ISO TEST CMAUT No. 2) ^:^PL lED ItVHGE I 1653 East Main Street nccfmtt. Nn Yon, t4eo9 usa ("8) «2 - 0300 - Phon. (716) 2U - JW9 - ra« %.^-, DXPABlllENT OF AOBIOULTDBI DAIRY AND COLD STORAGE COMMISSIONER'S BRANCH OTTA-WA.. OA.VJLI>Jk. The Testing of Milk, Cream and Dairy By-ProducU by Means of the Babcock Test ■T J. F. SINGLETON Ohuf Intpteior of Dmry PndueU Bulletin No. 45— Dairy and Gold Storage Seriea Determination of the Specific Gravity of Milk The Percentage of Acid and Casein in Milk Adulteration of Milk by Skimming and Watering The Percentage of Water and Salt in Butter The Percentage of Fat and Water in Cheese ■T J. F. SINGLETON Chief Inspector of Dairy Prodbcte Bulletin No. 46— Dairy and Cold St.. age Series Published by dirMtion of Hon. MARTIN BURRELL, Minister of Agrieulturo, Ottawa, Ont. OOTOBKB. 181S DIPAXnilllT or AQBIOULTUltl DAIEY AND COI.D STORAGE C0MMI8S i:.R'8 BRANCH OTTA'WA. CA1VAI>A THE TESTING OF MILK, CREAM AND DAIRY BY-PRODUCTS BY MBANS OF THE BABOOCK TEST J. F. SINGLETON, Chief Itupeetor of Dairy ProdueU. BULLETIN^ No. 45 Dairy uid Cold Storage Seriet. Published by direction of the Hon. Martin Burrell, Minister of Agriculture, Ottawa, Ont. 89182—1 OCTOBER, 1915 LETTER OF TRANSMITTAL Ottawa. November 2T, 1015. To the Honourable The Minister of Agriculturp. 8lH, — I have the honour to submit the raanu«cript for a bulletin on the tenlinir of milk and its product! by meansi of the Babcock milk tciter, which hua been prepaml under my din-ction by Mr. J. F. Singleton, Thief Ini«pp<"tor of Dairy I'ro Bttbcoclc tester in this connection call* for authoritative itiHtructinu in it«> niniiipiiln- tion, and the need of a bulletin of this description for distribution by this branch hu been felt for some time. Mr. Singleton is an authority on milk t.'stiuir. his training, and his experience •I instructor in milk testing at the Kingston Dairy School for several years before joining the staff of this branch, having q'lalificd him to deal with the subject in n ■cientific as well os a practical manner. It is not claimed that anything fundamentally new is presented in these poges, but the best practice* in the operation of the test arc set forth with such clearness and detail, that the bulletin should make a useful and reliable handbook for those who require instruction or information respecting the testing of milk, crsam, skim-milk, etc. I have the honour to recommend thot the ninniiscript be published ns Bulleti!i 45 of the Dairy and Coli "'♦orage series. . -lave the honour to be, sir, Your obedient servant, J. A. RUDDICK, Dairy and Cold Storage Comr'.issioner. yl82— U THE TESTING OF MILK, CREAM AND DAIRY BY-PRODUCTS BY MBANH OF THK BABCOCK TK8T IXTROnUCTORV. The Biiboook tP't flrrivi-*! its niinw from the oriiriniitor, Dr. S. M. Babcock, of the University o{ VViiconiin. Thia wiik the tint •utiufni'tnry Rhurt methcxl fur detprtniniiiR tho perccntHgo of fnt in milk, and ninot! it wa* mmie public in 189n widely ndoptod, partin ftuivpMftilly applied in the tMtinff of li THK TKSTINT, OF ., ILK. Till! apparatus employed in ninlst ot ii Miniple of milk •■insists of tour pi«>i-os : — («) pipett*; (ft) tost iiottle; (f) ucid measure or aeid burette; (d) centrifuge. The Ph'ktte. The pipette is a glass instrument used to meisure tlie saiuple of iiiillv rcMuirod for testing. Two different forms of pipette are in use wlileh are usually designated a-! the "ordinary pipette" nnd the "automatic pipette."' 8 The ordinary pipette consists of a glass tube enlarged into a bulb about midway between the two ends (Fig. 1). The lower stem of the pipette should be small enough in diameter to pass readily into the neck of the test bottle. It should also be drawn in to a small opening at the point, since if the opening is too large air bubbles will pass up into the bulb when measuring the sample and thus make accurate measurement impossible. The upper stem of the pipette is marked and the pipette filled to this mark contains seventeen and six-tenths cubic centimetres (17-6 c.c). The pipette should be so con- structed that the graduation mark is low down on the stem and quite close to the bulb. The construction of the automatic pipette is shown in Fig. 2. The novice will measure the sample more quickly and possibly more accurately with the automatic pipette than with the ordinary pipette. The automatic pipette is more likely to be broken and is more expensive. The Milk Test Bottle. The construction of the milk test bottle is illustrated by Fig. 3. The bulb of the bottle is about one and one-quarter inches in diameter, and should have a capacity of, at least, forty-five cubic centimetres (45 c.c). The neck of the bottle is about four inches in length and is graduated to read the percentage of milk fat when the test is completed. The graduation consists of ten main divisions numbered from zero at the bottom to ten at the top. Each division represents one per cent of fat and is sub- divided into five equal subdivisions, consequently each subdivision represents one-fifth or two-tenths of one per cent of fat. The Acid Measure and Acid Burette. The acid measure (Fig. 4) is a small cylinder graduated to contain seventeen and five-tenths cubic centimetres (17-5 c.c). Frequently an acid burette (Fig. 6) is used instead of the acid graduate. Each division on the scale of the burette represents 17-5 c.c. A stand with a clamp attached is used to hold the burette. The Centrifuge. The centrifuge (Fig. 6) is a machine for whirling the bottles in making the test It is fitted with swinging pockets to receive the test bottles and when the machine is in motion the pockets assume a horizontal position. The machine is usually driven by either hand power, or by a steam jet or turbine. Hand-driven testers are usually made to receive either two, four, eight, ten or twelve bottles, while the turbine testers will usually receive either twenty-four or thirty-six bottles. The two-bottle and four- bottle hand testers are not made with a covering frame. The larger capacity hand testers are constructed with a frame (usually cast metal) which closes in the bottles when the machine is ruiming, which aids in keeping the samples warm. Where steam is available and the amount of testing to be done will warrant the additional expense, the turbine tester is preferable as it keeps the samples hot while being revolved. The Required Speed of the Centrifuge. The speed at which the tester should be revolved is usually stated on the machine pnd varies with the diameter of the circle described by the bottom of the bottle in revolving. The following table of speeds for machines of different diameters is given by Farrington and Woll in "Testing Milk and its Products": — No. of Revolutions DiaiTjeter of of bottle Diameter of Circle. per Mln. Circle. 10 Inches 1.074 18 inches.. 12 •■ 980 20 " .. 14 " 909 22 Ifl " S48 24 ■• .. No. of R-^- olutlons of bottle per Min. 800 759 TO J 693 It'. I. Fig. 2— Up-to- dnte Pipette. Fig. 3— Milk Test Bottle. Fig. 4. Acid Measure. Fig. 5. When operating a turbine tester the speed must be ascertained by means of a speed indicator, which is applied to the spindle of the machine. The speed is regulated by varying the steam pressure used, which is indicated by a steam gauge attached to the machine. The operator must determine what steam pressure on the gauge will give the desired speed to the tester. When operating a ' hand-driven tester the number oi revolutions which the bottle makes, to each revolution of the handle, should be determined by counting. The diameter of the circle described by the bottom of the bottle when in the horizontal running position should be measured. By consulting the above table, the required speed of the bottle is obtained. The number of revolutions per minute required as indicated by the table is divided by the number of revolutions the bottle goes to each revolution of the handle. The result will be the number of revolutions of the handle per minute. Fig. C- Fip. 6. Kij.'. 1). For cxnmplo, if the bottle is foiind to complete twelve revolutions for each revolution of the liandle, ami the dinmotor of the circle described by the bottom of the bottle is fourteen inehes, wo find liy cnnsultini; the above tiihlo that for a fourteen- ineh diameter, the bottle must revolve imO times per minute: 909 divided by 12 is 7C (almost), wliieh is the number of revolutions required of the handle caoh minute. The tester should be placed perfectly livel on a firm bench and l)e kept well oiled. The Milk-Test Act. The Milk-Test Act which came into force January 1, 1911, provides that all test bottles and pipettes used, or sold to be used, for the testing of milk and cream in connection with tlie Babcock test must bn verified by the Standards Brnnch of the Inland Revenue Department, Ottawa. Glassware, when verified and found to bo correct within a specified liTiiit of error, must "be ineffaceably marked with the outline of a crown having within it the initial letter of the reigning sovereign." All milk and cream test bottles and pipettes, now in use or offered for sale, must be so marked. Making the Test. Before starting to make a test of whole milk see that nil glassware to be used is clean and bears the verification mark. Secliiing a Representative Sample of Milk. In testing milk it is necessary that tlie sample taken for testing represents the average quality of the quantity of milk to be tested. If such is not the case, the result of the test will, of course, be inaccurate and misleading. When milk is allowed to stand for evena short time, cream rises to the surface and in order to thoroughly mix the milk before taking a sample for testing, it is best to pour the entire quantity of milk from one vessel to another several times. If the quantity is too great to permit of pouring, it fchould be well stirred. After being thoroughly mixed a smaller qiinntity (three to six ounces) should be taken out and pat into a separate vessel. Samplino and Addikg Milk to the Test Bottle. The sample should be brought to a temperature of 60° F. to 70° F. and then poured from one vessel to another several times. Care must be taken that c'l the cream mixes back with the milk and that none adheres to the sides of the vessel. In pouring allow the milk to follow down the side of the vessel into which it is being poured. By so doing there is less tendency to partially churn the sample which would render the results less accurate. After the sample is thoroughly mixed, if using the ordinary pipette, insert the lower stem of the pipette into the milk and by suction of the mouth raise the milk above the graduation mark on the pipette. Quickly cover the top of the pipette with the index finger, taking care to keep the top of the pipette and the finger dry. By slightly removing the finger allow the milk to drop slowly from the pipette until it comes exactly to the 17-6 c.c. graduation mark on the stem of the pipette. The lower stem of the pipette is now inserted into the neck of the test bottle and the sample allowed to run into the bottle. The last few drops should be expelled from the pipette into the test bottle by blowing through the pipette. If using the " up-to-date " automatic pipette, have the glass petcock of the pipette open and insert the lower stem of the pipette into the milk By suction on the tube lead- ing from the large upper bulb, draw the milk up into i e pipette until the lower bulb is filled and the milk is overflowing from the upper stem into the large bulb. While the milk is still overflowing into the large bulb, quickly close the petcock. The lower stem of the pipette is inserted into the neck of the bottle and the petcock is opened to allow the milk to flow into the test bottle. As with the ordinary pipette the last few drops should be expelled from the pipette into the test bottle by blowing through the pipette. It is a rather common practice for operators of the test to blow through the pipette into the milk before drawing the sample up into the pipette. This should never be done as air is incorporated in the sample wliieh will affeet the result of the test. While the sample of milk is measured into the test bottle, the test is based on weight. The 17-6 c.c. pipette will deliver, of average milk, a definite weight — eighteen grams — into the bottle. Since tho weight of a given volume of milks of different rich- ness is fairly constant, measuring with the pipette is quite accurate and does not introduce any appreciable error. 89182—2 10 If several samples are to be tested, each sample should be given a serial number and a test bottle mariced with a corresponding serial number for each sample. A part of the bulb of the test bottle is usually frosted so that such a number may be written on with a lead penciL Aonixo THR Acid. The next step is the addition to the test bottle of the acid which is used in making the test. Commercial sulphuric acid with a specific gravity (Sp. Gr.) of 1-82 to 1-83 is used and should bo at a temiwrnturo of 60° F. to 70° F. The acid is measured in the cylinder provided for the purpose which is graduated to contain 17-5 c.c. After measuring the correct quantity of acid into the graduate it is slowly pr ured into the test bottle. When pouring the acid into the test bottle the bottle should 'lo held in a slanting position and if any drops of milk are adhering in the neck of the bottle, the bottle should be slowly revolved so that the acid will carry the milk down into the bottle. By holding the bottle in a slanting position the acid fl.nws down the walls of the bottle nnd lies under the milk. The aoid should never be allowed to drop directly on the milk, and after adding the acid to the bottle there should bo a distinct line between the milk and ocid. If the bottle is placed on the table after adding the ocid. care should be taken not to jar the bottle which will tend to partially mix the milk and acid. In case the acid burette is being used it is filled with a(!id to the top graduation mark. The test bottle is held in a slanting position underneath the burette with the top of the burette inserted into the neck of the test bottle. By opening the petcock the acid is olio wed to flow into the bottle. When the surface of the acid in the burette is lowered to the second groduation mark, the petcock is closed and 17-5 c.c. of acid will have been delivered into the test bottle. The sulphuric acid used in making the test is extremely corrosive. It is advisable to have, at all times, a bottle of liquid ammonia nt hand, and in case of any acid coming in contact with the clothing, a liberal application of the ammonia will neutralize the acid and prevent the drstniction of the cloth. Should the acid come in contact with the face or hands, wash immediately with cold water. Mixing s-ae Milk wn Acid. After adding the acid to the test bottle the milk and acid should be thoroiifihly mixed, shaking the bottle with a rotary motion. The neck of the bottle must not bo covered with the finger while mixing the milk and acid and care should be taken to avoid splashing particles of milk or curd into the neck of the bottle. As the milk and acid are mixed the milk is first curdled, then the clots of curd are dissolved nnd disappear, the mixture turns a dark chocolate colour, and becomes hot, due to the action of the acid on the milk. Placing the Bottles in the Tester. The bottle or bottles should, at once, be placed in the tester in such a way that the machine will be balanced. If an odd number of samples are being tested an extra test bottle may be filled with water and placed in the machine to properly balance it. If the machine is not properly balanced it will not run smoothly and the bottles are likely to be broken. Keeping the Bottles Warm. If the bottles are allowed to become cool, previous to, or while whirling, an ini'oniplete separation of fat will result and the reading will be too low. There is, of course, no difficulty in keeping the samples sufficiently warm when lining a turbine tester. When using a hand machine in a cool room it is advisable to partially fill the frame of the machine with boiling water before commencing the whirling. When using the two, or four-bottle hand tester, which has no covering frame, the j.oi'kets should be filled with boiling water surrounding the bottles. 11 WiiiKUNo THE Buttles. The bottles nro whirled lor live minutes at the proi»r speed. As pointed out above the bottle when in niotiuu uHsumcK a liorizoiitid pcjsitiou The bottle, rapidly revolv- ing, is subject to a force which tends to throw it awiiy from tho centre. This is known as " centrifugal force." This force is exerted most strongly on tlie heaviest parts of the mixture which work to the outside, thereby forcing the fat, which is lightest, to the centre. When the whirling ceases the bottle assumes a vertical position with the fat on the surface. If the machine is not run long enough or sufficiently fast, the separation of fat will not be complete. ADDixa THE Hot Watei; to the Test Bottles. Hot water is now added to the bottle to float the separated fat up into tho neck of the bottle so that the percentage may be read. Tlie turhine tester usually hiis a sninll pail attached for heatinp anil iiddiii;.' tlie water to tlic test bottles. The pail is fitted with a small rubber tube leading from tlie bottom of the pail, into the end of which is fitted a piece of glass tubing drawn to a point similar to the glass of an eye-dropper. There is a spring pinch cock on the rubber tubing to shut off tlie water. If using a hand tester and only a few samples are being tested at one time, the pipette will answer very well for adding tlie water to the bottles. If many samples are being tested it is advisable to provide such a pail as described above and attached to the turbine tester as shown in Fig. 6. IJain watei- or condensed steam is preferabh; to hard water as it will give a clearer fat eolunni in the finished test. If hard water must bo used, a few drops of sulphuric acid should be added to the water bei'ore it is heated. Adding acid to hot water is dangerous as it is liable to be splashed on tho faoe. hands or clothes of the operiitor. If a turbine tester is being used a temperature of 140° F. to 160° F. will be high enough at which to have the water for adding to the bottle. If a hand machine is being used th(> water should be made much hotter, in fact there will be no disadvantage in usitig boiling water. As far as possible the work should be done in such a manner as to have the t' iniier:>tiire of the siimi>les 1 ctwfen ^"l)'-' Y. nrnl 1+0° T". when the test i- completed, aii dividers are »pr<«(l iiiitii the pnintft are farther apart than the fat column is long, then one point is placed at the extreme lower end of the frti column, and the divider^* slowly <'liised until the other point is ut the extreme upper eid of the fnt coliinin. One point of the dividers is now placed at the zero mnrk on the scale and the other point will indicate on the scale the correct readincr. For instance, if the length of the fat column, ns shown by the dividers, is three main divisions ond four subdivisions, the reading is 3% per cent. This may also Kilf. !l. be expressed as 3^jn per cent or 3-8 per rent. This would mean that iu each one hundred pounds of such milk there are 3-S pounds of milk f:it. Cleaxisc the Bottlks. As soon as the readings of fat are tnkon tlio bottles should, while still hot, be emptied and rinsed with warm water. Tlii-.v should next ho thoroughly washed with hot water to which has been added n little of some good washing compound, using the brush provided to clean out the neek. The bottles should be again rinsed with hot water to thoroughly remove the washing compound from the bottle. Even with such washing the bottles will in time become coated on the inside. To prevent this an occasional cleaning, using a very strong sohition of washing compound, with some shot in the bottle, is advisable. Sulph\irie acid, to which luis been added as much bichromate of potash as the acid will dissolve, makes an excellent material for cleaning any dirty glassware, and the same solution msiy be used many times. DAnK-C0L0UI!ED OR BfliNT KkADINOS. If, when the test is completed, the fat column contains black specks or is too dark in colour, the test is not satisfactory and a duplicate test should he made. Dark-coloured or burnt readings may be due to one or more of the following causes :— (a) the milk, the acid, or botli. iii'itig at tno liish :i temperature (over 70°) ; (6) too much or too strong acid; (c) allowing the acid to fall directly on the milk; (d) allowing the bottles to stcnd too long after adding the acid before mixing. LiGi(T-Cou)ti;i:n or Cuhdv Ukadixos. If ttlion the test is completed the fat column is too liglit in colour or shows curdy, the results of the test may be too high and a second test should be made. Light-coloured or curdy readings arc due to one or more of the following causes :— (a) the milk, the acid, or Loth, being at too low a temnerature (under 60°) ; (b) too little or too weak acid; (c) not thoroughly mixing the milk and acid before whirling. 14 Acid supplied for testing is not always of the proper strength. If tho test is carefully and properly made, a dark-coloured or burned reading indieait* ikat the aeid M too lirong, whiln a light-coloured or curdy reading indicatei that the acid it too weak. If the auid is only sliithtly too strong, satisfactory results may be obtained by using somewhat less than 17S c.c, ond if the acid is only slightly weak, using a little more than 17-5 c.c. will give satisfactory results. Acid that is much too strong or much too weak cannot be usod satisfactorily. Acid, if left exposed to the air, becomes weaker by absorbing moisture from the air, consequently acid of the correct strength should be kept stoppered when not in use. Acid, which is too strong, will in time weaken to the correct strength if left uncorked. If a cork stopper is used, the acid will char the cork and the acid becomes dark. A glass-stoppered bottle is prefenible. Composite Samples or Milk. A composite sample of milk is u quantity of milk composed of several smaller simples taken from different sourct-s and should represent the average quality of the different quantitieg from which the samples are taken. Cheese factories, which divide the proceeds on a basin of the test, use the com- posite sample and the great mojority test only monthly. A tightly stoppered bottle is provided for each patron, and some means provided to identify each patron's bottle. A convenient way is to gum a label bearing the patron's nome, or a number to designate the patron, to each bottle. If the label is covered with two coats of shellac, the bottle may be washed without injury to the label. The Use of a Preservative. Some chemical is used as a preservative to prevent souring and other fermenta- tions. Since nearly all strong preservatives suitable for this purpose are very poison- ous, some colouring matter is mixed with the preservative which gives the sample a distinctive colour and thereby indicates that the sample is unfit for use as a food. Preservative may be purchased in tablet form from the dairy supply houses. These commercial tablets are usually composed largely of corrosive sublimate and are very satisfactory. Powdered corrosive sublimate is also very efficient. If this is used a small proportion of magenta should be mixed with the corrosive sublimate to colour the sample. In case one is troubled with mould growing on the walls of the bottle a few drop« of formaldehyde may bo added to the sample. This will prevent the growth of mould. The Quantity or Preservative to Use. The preservative is added to the bottle before any sample is put in. No definite quantity of preservative con be said to be the correct quantity. The correct quantity to use is the least that will preserve the sample efficiently, and this depends on : (a) the quantity of milk that will be in the sample bottle; (b) the length of time over which a sample extends; (c) the temperature at which the sample will be kept; (d) the degree of ripeness of the milk composing the sample. An excess of corrosive sublimate affects the casein in such a manner that it spcma more difficult to dissolve and more shaking is required in mixing the milk and acid in the test bottle. Sampling Milk for the Composite .,r. The sample of milk added each day to the composite jar should not only represent tlie average quality of the quantity from which it is taken, but should also be propor- tionate to the quantity. Two methods of taking the sample are in common use: (a) the small conc-shapotl dipper (Fig. 10) ; (b) the sampling tube (Fig. 11). S Kijc. 10. Fig. 11. The small cune-sliupvd or " ounce dipper " as it is commonly called does uol take a Bani|ilo proportionate to the (|uantity of the milk being sampled. Since milk deliven»d at ii ohceso fui-tory is well mixed from the iiKitiition received on the wiigon and by i)ouring into the weighing cun the sample taken by the ounce dtp|)er will represent the rrutive, or to over-ripe milk having [m'u .uhM to tho jar. In mcli ni«is a vorv imall quantity of powdered lyo may be added to the sample and the tamplo poured from one veaai'l to another several times. The lye n-'utrnlifcs the acid and when suffi- cient acid ii neutralized the milk airain becomet liquid. The lyo ohoiild be added in small quantities, pouring the sample several tinien after each adilitioii of lye. In this way the use of an excessive quantity of lye may \>e avoided. When the lumps of curd disappear and the sample becomes fluid it is samn1e) gramme or an eighteen (18) gramme sample, the bulb should have a volume, at least, eiiual to that of the ordinary ten (10) per cent iri"t bottle. Both tho six aua one-half-ineh nine-gramme bottle nnd the nine-inch cightcen- grnmnio bottle have necks of smaller bore than tho six and onc-lialf-incli eighteen- grnmmo bottle. In tliis respect citiior of tho fnrmcr is prefiTaMe to the latter, since the smaller the bore of the neck tho less error tlioro is likely to Ih? in reading tho per cent of fat. In using tho nine-grannno buttle, however, ouy error in wei^jhing tlie sample produces twice .ns great an error in tho tost as tho same error in woighiug wi'l produce in tho eii,'liteen-grammo bottle. This is roaiHly soon from the following calculation : — If a nino-gramme sample in r. niiie-granimi^ hottle rends W por cent fat, each onf" gramme of the sample roads r5C^!)=4 por oout fat, nnd onoh ono-half gramme roads 2 per cent fat. If an eighteen gramme sample in an oifthtoon-grnmmc bottle rends Of) per cent fat, c ono gramme of tho sample roads 36~lS=-2 ikt cent fat, nnd each one-half gran --nds 1 por rent f.etto iiinccurnte, Theae are:— (u) Variation in richncs* of cniim.—Crenm iiiuy t»'«t at low at 15^^ of fat or aa Liph lit 50', . / the p«'r cent of fat in cream iiicrraMii, the weight of a given vilurae (Iccrenscs. Therefore a iiipctte, which will mcnoure a sample of the proper weight from a low letting cream, will mcnture, from a richer crcnm, n tnniplo that will be too liifht. (b) Gat and Air in the crMW.— More or Kh gns duo to touring or other fcrmcutn- tiont i* prcM'nt in crcani. Tho hcav.v body of the crenm tendt to retain theto gates in the cream niid therefore reduce the uriulit of cream which will ho mcniured by a pipette. This will not hnvc to great an intluenco if the cream it warmed before 'he tnmi>lo it measured with a pipetU'. a* the wariniiik' reduces the body of tho cream no \hat the gat will, to a great extent, escape. This is illustrated by the following table which also illustrates the difference between the resuHs obtained when the scale is use. l( 1 =^' iir CrMiiii. Cold Crea I'ilirtti-. i (X..i.-.t.) III. McbIim. \\ nriii Cn^aiii . Scnie*. I'ilH'tt... Pipt'tti'. A :i(i 41 3!) R St) 5 :m ^ .^■« .'•. :«i 5 34 C S2 .11 .•. 31 .'. 3'-' 31 ft 1).., 31 3J 6 3i; .<« 5 :« .-• K 36 3 ?<, w :v.r> :i."i ."i r «i 31 .-, 31 ... 31 .1 (J :« 5 34 5 .■M :«; :« H su 30 2!! :> .to 29 5 Thcie HgurtM »n typionl of iIm< rmulu obUiniHi in Mveral mure luch taat*. Prao- ticalljr no iliffentniw, bpyoiiil • n>a*oiialtl« limit <*( vrrur, ii iiotin<ain|)li> i* warnM>il to IW) doKrco* befor* •amiilinic. thuuffh in lunie fttiri a ilivhtly lowir n'mlinic i* imlifttl wh> lh« ■mii.tliv wa« tulii'ii witliuut warniiiitf. ] » i\\titv |K»iiil)U> that in iiM-i-ial ca^i — with very g»»*y crviim- thi< error would nhow •n-ntcr than in thiiH> fliruri'x, a* ilu>ttfi numitli'* lumnHi quito i'ifan in Huvour. (!•) Cri-am mihrrxHO to thf wullt of lhillr. Sonm cn-iini mlhi-ri>4 !■> the walU uf tliii |ii|>i'tti* untl if thin in not thoruuithly riiiM'd olT and uddi-d to thu text bottle tlio mult uf thu ti'Kt will be inoccuratc. Thk I'm*; or ScALKM iciii WKHiiiiNo Sami'lkm or Ckkvm. In onliT to HViiid iUvm- Miurifn of rrrur in nu'uxurinir i'ri>uni «uni|ilt'>, m-alut huvv IxH'n dfvixi'il f creiini minipli-M of fithrr nino (IM |{riitnnii"< i>r riuhiirii (IH) (rrninnitM into tln' iNittliM, Crcnni t«'i>tinif wmIim nrc niii-itriii'ti'il i>f iJilTiri'iit (>ii|iiicitii'», S(inn> Willi'" liiivr i ivipiirily nf Inilvr I. "I liutllr* ( l-'iir. i:t), rhnt \* iti'iimi samples may be wuigiieU into each of twelve bottles with oi:e balaiifins; t' the scales. Other M-ales have eapacifies of four bottles, two bottles or one buiile ( i . U). The fewer the Im'tles the seuleg will earry the more accurate will be 'be v.i'KfhinK ami the loiiRer will the work require since the scales must be balaiioeil nidro frequently. The scales should be kept in u dry place to protract the bearinprs frnii: rust which would soiin render the .scales inacciir :it<'. When in use the scale sbimbl lie p'ac.vl i>m a firm. Iri-fl ,bi'lf or tabl.'. In usinjj the twelve-bottle scale the bottles are inimlierix' and placed on the scale. The weisht on the weiRhinpr Iwam is placed ai the extreme left notch on the beam and the scale is then balanced by niovintr tl:e ball on the tare beam. The b.nll or weifrht on the wciRhinfir beam is then moved to the ritrht, to the nine CO) (rramnie or eiirliteen (IS) (tramnie mark, deiwndiiiK on thr style of bottle beins u.sed. and cream is added to bottle No. 1 until the scales aprain bnlanco. Fsnally the weight is ngnin moved to the rijrbt and the weiffhinjr repeated into battle No. 2. This is repeated until the bottles on tlie left pan of the scale each contain a sample, when the weight on the beam is moved to the left and samples weijrlicd into the bottles on the right arm of the scale. A better practice is to wi'igli a sample intf n bottle on the left pan, then 89182—31 w move the weight back to the U'ft and weigli u suiiiplu into a bottle on the right pan, weighing alternately into bottles on the right and left puns until all bottlea contain samples. The four-bollle scale is used in the same manner as the tweUo-bottle scale, except that nine (!)) and eighteen (IS) grnmiiie weigiits are used on the pans of the scale instead uf the weight on the notelicd beam. With the one-bottle scale (fig. 14) after balancing the scale with the bottle placed on the left pan a nine (9) gramme ** ur eigliU'on (!>) i:rrainnic \vi iuht is placed nu tlic ri^bt pun of the scale and the sample is tlu'ii woiiibcHl into the bottle. SaMPI.INC Cur.AM l""l! Tkstino. In sampling ereain for tesliiig siiceial prd'aiitioiis must be taken to secure a sample which represents the average quality ti> lio tested. It is more difficult to get a representative sample uf a quantity of iTi'ain than it is to <;t'.t a representative sami (■ of an eiinal • ;antity nf milk, since tbi> rre:im ibu^s not mix as readily. If circumstances pern)it it is lu'st tci pour tlio quantity of cream from one ves.sel to another several tiinos. If pouriiiir is nut practicable, tb(> (ream should be thoroughly stirred by means of a stirrinir rod (Fiir. l.'i') Ci.n>tructod for the purpose. i"i i:. If the quantity of cream is thnrouiihly mixed a small dipper (Fig. 10) will he (piite satisfactory fur lakiiii.' tlic s:nuple. Owing to the difficulty of thoroughly mixin.ii a can of cream, several special ileviees have been recommended for taking the sample. Of tbe-e the " McKay Sami)ler " (Fig. 11) is i)robably the most satis- factory. This is ('(instructed with two sliitte(l tubes, one inside the other. The tubes are turned to clo^c the slot and the ':auq)ler inserted in the cream to the bottom of tlie can. The slot is. then, opened to admit the cream to the tidie, after which the slot is closed and the tube withdrawn. The sann.do thus taken is a small column of cream exteiuling from the bottom of the can to the surface of the cream, and is repre- sentative both of the quaJihf and (luantiti/ of the cream sampled. SI Pbepabisg and Weiohino the Sample for Testing. The sample of cream to be tested should be warmed to remove any lumps from the cream. Should lumps be pre?c>nt, which will not disappear upon warming, the sample should be poured through a fine wire strainer and the lumps broken up nnd forced through the strainer. The sample is then carefully poured from one vessel to another several times and, by menus of a pipette, cream is transferred to the bottle on th(> scale until the scale balances exactly. If usinpr a nine (9) gramme sample in a nine (9) gramme bottle, nine cubic centi- metres of water should be added to the 8nmi>le in the bottle from a nine oubic centimetre pipette. The full quantity of acid (17r>ec.) will be required with a nine-gramme sample, if nine cubic centimetres of water have Seen added to the bottle. The addition of water in the bottle usually gives a clearer fat column. For the same reason it is advisable to add n few cubic cpiitimptros of water to the ciarhteen- gramnip paniplo. The addition of watnr, howrver, ncrrssitntns the use of more than the usual (|uantity of arid, and care must he ta!:en not to add toi mncli wnt(^r to the eiglitc'di-prammo sample, as the bulb of the botth^ will not b(^ la'ge rnoiigh to hold the extra acid required in addition to the water. Measuring Cream Samples with the Pum:tte. When strict accuracy is not essential fairly correct results may be obtained by using a pipette and measuring the cream into the test bottle. Since cream is lighter than milk, the pipette used for measuring the sample into the eighteen-gramnie bottle should be larger than that used for testing milk. A pii)ette with a volume of eighteen cubic centimetres is used irt connection with the eighteen-gramme bottle, and after the sample has been measured into the bottle a few cubic centimetres of warm water should be used to rinse the pipette, which rinse water is added to the bottle. For measuring the sample into the nine-gramme bottle a nine-cubic centimetre pipette ia used and nine cubic centimetres of warm water is used to rinse the pipette and is added to the sample in the bottle. As previously stated, the presence, in a cream sample, of gases due to souring or other fermentations, or of air incorporated by pouring, while introducing no appre- ciable error when the scales are used, will produce an appreciable error if the pipette is used. The presence of air and gas in the cream lessens the weight delivered by the pipette. Warming the sample reduces the body or thickness of the cream, facilitating the escape of the gas or air from the sample and to a great extent prevents error from this source. For this reason especial attention should be given to the warming of the sample when the pipette is to be used. Reading Cream Tests. Especial care should be taken to have the fat at a temperature of 130° F. to 140° ". for reading. Owing to the volume of fat present in the nwk of the cream bottle, considerable error may be introduced by having the samples too hot when read. Cream samples also require longer than milk samples to become adjusted to the temperature of the water bath. Unlike reading the tests of milk, the reading of cream tests is not taken from the extreme points of the fat column but from the bottom of the fat column to the bottom of the meniscus on the surface of the fat column (Fig. 17). The reading should be taken from A to B, not from C to B. The Use of Oil in Reading Cream Tests. Owing to i' difficulty of determining where the bottom of the meniscus is, a few drops of a lig? r than the fat, so that it will not mix with, but float on top of the fat. The oil is conveniently added to the bottle by means of a pipette, allowing it to flow down the wall of the neck of the bottle. The miniscus is raised up on the surface of the oil leaving a sharp distinct line between the fat column and the oil. The reading should be taken from this line to the bottom of the fat column. This oil may be secured from any of the leading; dairy mipply lionsos, or may be prepared by any one requiring it. A mineral oil sufficiently light that it will not mix with the fat must first be secured. An oil sold, by one of the leading companies, under the trade name " Albolite " is very satisfactory. Alkanet root, which may be obtained from any good drug house, is used to colour the oil. One ounce of alkanet root will colour one gallon of oil. The alkanet root should be rolled in doiiblo ply chctY-o cloth and soaked for twenty-four hours in the oil. The alkanet root is then removed and the oil will be of a light reddish colour and ready '.'or nse. Composite Samples op Cream. While many creameries, and the number is increasing test each delivery of cream received from each patron, many still use the composite samples and test either once or twice each month. What has been said regarding composite samples of milk will also apply to com- posite samples of cream. The ounce dipper is not as satisfactory for sampling cream as for saii4>ling milk. Since it is more difficult to thoroughly mix cream than milk and since the deliveries of cream shew greater variation both in quality and quantity than deliveries of milk ^ome such device as the McKay sampler already described should be used. Evaporation of Water fri Composfte Samples op Cream. Especial care should be taken to see that the sample jars are tighly corked to prevent evaporation of water from the jar, which would cause the samples to test too high. To illustrate this point, some years ago the writer after testing a number of composite cream samples at the end of a month left the s.implcs uncorked in n cold room for seventeen days and again tested the samples. The tests were as follows: — At end of month. Seventten day later. A 40 48 B 25 88 C 40 4S D 30 81 E 21 24 F 30 82-6 G 29-5 34 These figures illustrate plainly the necessity of keeping the conipoaite jars tiphtly corked. The extreme variation in sample A, is accounted for by the fact that there was very little cream in the jar and the evaporation was higher proportion- ally than in the other jars. Testing or By-Phoducts. DETERMINATION OF THE PER CENT OF FAT IN 8KIM-MILK AND BUTTERMILK. Under the moat favourable conditions of separation and churning of crenm there is some fat lost in the skim-milk and the buttermilk. The Babcock test may be used to determine the extent of these losses. B FiR. 16. 40^^ 35 10- ^ 30—^ c5 — = 20 — = 15-== 5-^ B rig. 17 THK DOUBLE-NECK BOTTLE. A specially constructed double-neck bottle (Fig. 16) is used. The larger neck is to admit the skim-milk or buttermilk and acid to the bottle and should be conducted down close to the bottom of the bottle. The smaller neck is graduated to read the percentage of fat. The older st.yle of double-neck bottle was usually graduated so that the entire scale consisting of ten divisions represented one-h.alf of one per cent of fat. Each division would, therefore, represent five one-hundredths of one per cent of fat. "Most double-neck bottles now on the market have either five or ten main divisions, each of which represents five one-hundredths of one per cent of fat and is subdivided into five equal divisions. Each small division, therefore, represents one one-hundredth of one per cent of fat. In testing skim-milk or buttermilk especiul care must be token to hare all glasa- ware perfectly clean, as a slight amount of fat in the pipette or bottle would seriously affect the results. A 17-C cc. pipette is usp«l to measure the saraph and 17-li cc. of arid is urdinarily used. It is probnble thnt a sliphtly more perfect separation of the fat will be obtiiinod if the milk and acid are cooled below 60°F. nnd nlimit 2flcc. of ncid used. Care must be taken in niixiiiR the milk niirlass instrument which floats upii.-ht in the rHpaiil. constructed with a small bulb on the lower end, wliicji is biiuied with either nicrcnry or fine sliot, and a larger liellovv bulb above, to the top of wliich is attached a slender stem with a trnuluatcd paper scale insiilc from which to ri>.id the specific pravity. Tho use of such ,in instrument for determinin;,' the specific irravities of li(inids is based on the natural law tliat "A ho<\y lloiitiiur in a li(iuid will displace a volume of that liipjid cipial in weight to the wcicht of the body floatluLr." The liydronu'lei- sinks in the lii|uid until it h:;s displaceil a vnbime of the li(juid eiual in woiirlit to the weisht of the hydrometer. In constructing hydrometers for deti'rniininsr the specific gravities of different Tuiuids, the weiirht of shot or mercur;\' in the lower bulb, and tho size of the hollow bulb above, are varied, ('cppndinc: on tho specific crravity of tho liqnieu just at the surface of the liquid. Thi> llKliter the l;<|uid, tlic t'ariher will tlie hydrometer aink into the liquid, and the hi>avii>r the liquid, the hijrlier nj) will the hydrnmeter float. Since liquids exjiand and become lishter when wanned, and contract and bcoine heavier when cooled, an hydrometer will oidy civo a correct rcadiii,;; when used iu a liquid at the temperature for which it is constructed to be used. TiiK Lactometeh. Such an hydrometer is used to determine the specific gravity of milk and is usually called a lactometer. The lactometer conmionly used in determining' the specific gravity of milk in known ai the " Qucvenno " lactometer. It ii uiuolty conttrueted •• ■ combined thomiometcr nnii hydromctfr (Fig. 1) and i* coiwtructed to give a correct reading when ukmI in milk at a tcmperoturo of 60* F. r\t. \. The icalo on the lactometer i» usually grudiiatod from 14 iit the tup to 42 nt the bottom and each of the twcnty-eiisht (i8) divinionsi botwcoii 14 luul 42 i» called a lactometer degree. If the lactometer i» constructed an a combined thermometer and hydrometer, the thermometer scale should bo above the lactometer KcaU- in the stem, ho thot the temjierature may be read when the laotomet.'r i» at rest in the milk. In taking the lactometer reading of milk, a glass ct tin cylinder about one and one-half inches in diameter and twelve inches hitjli (Fig. 2) is noci'sxnry. To bo strictly accuriite, the milk should be brouKJit to a temperature of 60° F. and after carefully pouring the milk from one vessel to another a few times to distribute the fat unifi>riiil,v throughout the milk, the cylinder is filled with milk to within iibKiit one and one-half inclu* of the top. The clean, dry lactometer is mnv gradually lowered into the milk in the cylinder until it comes to n-st and lloats steadily in the milk. The point on the scale which showi* nt the surface of the milk is at once road and recorded and is known ii» the lactometer reading (L.R.). PIK. 1 The Influence of Diffkhent Tempkhatures. As pointed out above, ns the temperature of the milk is raised above 60' F. (the tempcnitiire ut whic-li the luctomotor is constructed to be used) the milk expands and becomes less dense; consequently, the lactometer must sink farther into the milk to displace its own wciRht. Since the luctometcr scale is graduated from 14 nt the top to 42 at the bottom, the lower the lactometer sinks the lower is the readini.'. On the other hand, as the temjM r \ture of the milk is reduced below 60° F. the milk contracts and becomes more dciisi- and the lactometer does not sink as low in the milk to displace its own wcJKht. This means a hiffhcr reading on the graduated stem than if the temperature was nt 00° F. In order to avoid the necessity of brinping the temperature of each sample of milk to exactly 60' F., the lactometer rcadiuR is us\ially taken at whatever temperature tho milk may lie. provided it is between 50° F. and 70° F. It will bo found that if a sample of milk has a lactometer readiiiff of say 30 at a temperature of tW° F.. the sample will have a lactometer rending of approximately 29 at a temperature of 70° F. and of approximately 31 at a temi>erature of .50= F. From this, a rule for making corrections to the lactometer reading on account of the temperature bciuR above or 1k>1o-v 60° F. is deducted, viz., for cnch dejrree that the temi)oraturc exceeds 60° F. add A or -1 to the lactometer ro.idini? and for each degree that the temperature is less than 00° F. substract t\, or -1 from the lactometer rending. For example, if a nuuiple of milk .=hows a lactuiiicter rc-adiiif; of 20-5 nt 67° F., the correct rending would be 29-5+ .7 = .'iO-2; and if a sample shows a hictometcr reading of say 31-6 at 52° F.. the correct reading would be 31-5 — S = 30-7. This rule gives fairly accurate results when the temperature at which the reading is taken ranges b«tw««n SO* F. •11(1 70° F., but U itrictly accurate re«iilt« are deiired. it U beat to brinff the temperuturo of tho milk to exactly t)0' F. before taking the lactometer reading lo that no rurn>ction nn nccuunt of ti'mprrature will bo ncceaaary. In taking a lactunictur reuding of n lampio of milk, the milk «houlil not bo allowtxi to *tand after jioiiri „•, lirfiiro taking the rradiiig. If tho fample is allowed to itand, tho cream rites to tho tnrfaoo and tho bulb of tho lactuniotor will be in par- tially akimmed milk which in hcuvier than the whole milk ; conMNjucntly, tho lactomtter will not link n^i do liu'tonictiT rcudiiur of (rv*\\ i 'I'; will UHiially Ihi uIhiuI ono degree lower than it will 1m' from two to tlirco lumrs hi er. Uht\imnu Tin; Si-Kciric (Jhavitv jhom tiik Lactomktkh l{K\niNii. In onlir to obtain tin- j-iticitic gravity of milk from tho hu-tomctor reading, 1,0(K) in adili-il to tlir Ijn'tonictcr ri'aeitlo Orauty. For exiiniiili', if tlio correct laetoiueter reiulini; in 30, the .•ipecitic gravity will k' 30 -f 1(M)0 lOMO lOOU 1000 «10.TO In order to obtain the lactometer reailintr of milk from the spccilic jtravity, the specific gravity is multiplied by 100d by means of the Babcock tcst- C.*LCta.\TISO IIIK PkIK KXTACK OF Sol. IDS NOT FaT IX JIll.K. The perccnt.aBc of solids not fat in milk is calculated from the percentafje of fat and the lactometer reading. Several dilTcrent forinnlas have been worked out for calculatinjt the pereentafre of solids not fat. The one most commonly used is to add the percentage of fat to the lactometer readinir at fiO° F. and divide the result by 4. c S N F - li' l!^ "*■ ^•'^- "* ^'^' For esample, if ■ Mmple of a Ik tmU 3-5 per cimt of fat with u luutoiuetor readinf of SIS at to* % 8.N.F. 3S>31K .ia -8.76. Another formula comnior' . j !« to multiply the per c«ut of fat by 0'!, dlvida the lactometer rpndinir hy 4 nna ddd the two renulti: — %8.N.F. = Fatx0.2*^'"' Fnitiir thi« formula v.th n lumplo tc>i:!l.'>. of .-kinmird milk from I-ii.-.l' to aliout l-():iT. Tin: I-Ikkcit ok Skimmim; oi! PviiTUi.i.v Skimmim; Mn.K. It will 1)1' readily iiiuler-'ood tliat reniovlncr part of the en-am from milk will oaiise the milk to test lower in fat content. Since fat has a speeilic (gravity of 0-9, whi.li is (-onsiderably Ii-ss than the speeitie ftravily of milk, removinir i>art of the fat from milk by mean-* of skinnninir will cause the partially skinniied milk to have a hi;,'her speeitie L'ravity or hi^rlier laelooiefer n-adimr than the whole milk had before beinj; partially skimmed. Konsrhly speakiiiff, t'.ir each one per (-ent of fat removed by ^^kimininir, the lactometer reading of the partially skimmed milk will be increased by about one det^ree. For example, if a sample of milk test.^ 4 per cent fat .nd has a lactometer readiiitr of 'M, rc-nioviiifr 1 per ci-nt of fat, that is, skimmintr it down to ,'5 \WT cent of fat, will i'lcnjiise t)iri««< with wii'h 1 |K'r cent of fnt nmnvi'd hy ■kimtninir, lh« |>«>r wnt of nolid* not fnt would not be iifff><>t)>d. In aptuiil pnirtifp, it ii unuiilly fount! tliitt imrtiiilly nkinuninir milk •litrhtly iniTcnitHi tim pintiiin< 4 jht ictit of fnt with n liiitMm..ti.r r.-in'itin of 32 fth;it i« II (Jr. ..f l.(i:i'.>) iin.l !» |ht .cut nolidn not fat. ono tfiill..ii of ni.-h milk will weiifh 10. ;i-.' pniimlK. If one Knllori of thi-< milk is mix.''i of «iich milk uml wafir will wi'iirh 10. IB pmitidK, or hnvf n Sp. (Jr. of 1 0|(i „r ii In.tonu'f.r n-mlinK of 1(1. From thin we m.. thnt nd-75" " " lot) x O-T.") = T5 lb. piin' milk. u That is, f|.7.'5 pounds solids not fat are present in 75 pounds pure milk, and since we have 6-7.5 pounds solids not fat in 100 pounds of adulterated milk, it is evident that 7.') pounds of puri^ milk liave been increased to JOO pounds by the addition of water. That is in each lOO jjounds of watered milk there are TOO - 7.5 — J."> pounds of foreign water or 25 per cent of foreign or extraneous water. Since the calcidation is similar in all cases, we may deduce the following formula: — The per cent of extraneous water —- per cent solids not fat in adulterated sample x 100 100 per cent sol'ds not fat in the p\ire sample. That is, to find the per cent of extraneous water, multiply the per cent of solids not fat in the adulterated sample by 100, divide the product of this tuiiltiplication by the per cent of solids not fat in the pure sample and subtract the result of this division from 100. The difference will be the per cent of extraneous water present. 11 Dktkiimi.vation of Extknt ok Aim i.tkiution ok Milk Both Skimmko and Watkred. In case a samplf i* l)oth skiiniiUHl and watcrcil, tlio above forin\ila for (li'tcrniininff the IXT «>nt of for«'i>?n water present, liolds Rood. To illustrate, if we have an adnlU'rated ^an)Ille showinjr l"r fat, n liictoniofer reitdinK of 22, mid fl% solids not fat, and a eontrol sample showiuK 4% fat. a lacto meter reading of 32 and d^i, solids not fat. it is plainly evident that the adiilt.Tnted soniple is both skimmed and watered since while the fat is reduced by one-half (from 4% to -2%) the lactometer is only n-dueed about one-thir fat in adult, sample x Cr solids not fat in pure sample. % solids not fat in adult«Tat<^l sample. That is, if a sample is both skimmed and watered, to find the per cent of fat abstracted, nmltipiy the per cent of fat in the adulterated sample by the jier cent of solid.s not fat in the pure sample. Divide the product of this midtiplii-atioti by the i>cr cent of solids not fat in the adulterated sample and stdttraet the result of this k in alkalis, as an indicator. By ineabunng the ed two or three times nnd filled to the O mark with the alkaline solution already prepared. The alkaline solution is slowly dropped into the acid and constantly stirred until tlie niuhal point is reached. The number of cubic centimetres of solution used siiould lie noted and the neutralization pt^rformed a second time to verify the accuniey of the result. ]f the alkaline solution is too strong less than 10 c.c. will be required to neutralize the 10 c.c. of standard ncid solution. For example, if 9-2 c.c. of alkaline solution neutralize 10 c.c. of acid solution, the alkaline solution is too strong and -8 c.c. of water must beadded to each 9-2 c.c. of solution. By measuring the volume of solu- tion prepared, tlie necessary v.dume of water to add may l>e ealeulated. For example, if "iOOO there are 5,000 c.c. of the solution, the water to be added would be ; .,S = 435 y ■ j5 (almost). This volume of water is now added to the solution, which is thoroughly inixi-d and tested for accuracy. If tiie work has been carefully done, the solution should be of th:? correct strength, that is 10 c.c. of the alkaline solution should exactly neutralize 10 c.c. of the acid .solution. If the alkaline solution proves to Ik- still too struiir. more water must be added, if too weak more caustic soda must be added. In standardizing the alkaline solution, two or more tests should be made each time to ensure accuracy. As soon as the correct strength is obtained, the alkaline solution should 1)(! tightly corked in a glass bottle or buttles. Earthen jugs arc not suitable as containers for the solution. If the solution is not being prepared in a bottle, but in some other vessel, the bottle or bottles to receive it should be thoroughly clean and rinsed with a little of the solution before being tilled. If a delicate scale and gram weights are not to be had, the caustic soda may be dissolved in a little water, making a strong solution. This strong solution may be gradually added to the water, testing after each addition of the strong solution.' If too much of the strong solution is added and the solution being prepared is made too strong, it is reduced by adding water. The solution can soon be brought to the correct strength in this manner. STRENGTTI OF IXDICATOU SOLUTION. The strength of the phenolphthalein solution used as an indicator may bo varied considerably without affecting the results of the tests and different strengths of solu- tions have been recommended by different authorities. Prof. Walker has recommended the use of a 1 per cent solution in connection with the Walker method of determining 15 the per cent of casein in n.ilk unci nuch a solution is aUo satisfactory for use in c.m- nectjon w.th ho ac.d.„,c.tor. A 1 per cent solution is prepared by dissolving Vra«. of p!, .ioli.thulein m 100 c.c. of 95 per cent alcohol. ssoiving i grau. TESTlNti CIIEAM, SKIMXfll.K, BUTTERMILK AND WHBY. n.ilk'^'l'!ntr,"','lir"' i' f '" ■""! '" ^^■'^•""""' the per cent of acid in crean,, skin.- DETER.M1NAT10X OF THE PER CENT OF CASEIN IN illLK BY ME VNS OF THE WALKER CASEIN TEST. -UtANS fl,n ■'"• ,'l'-''7""''"« t''«. I«"f ''^t of casein in milk by moans of tb.. Wnikor method he ac.d.meter as descnbed in this bulletin is usc.l. In ad.lition to the aeid "m tor" It IS necessary to have: ""luuKror, 1. A ICS c.c. pipette. 2. A 2 c.c. graduate. 3. A bottle of neutral formaldehyde solution (40 per cent). The neutral formaldehyde solution is prepared by adding a few drops of phenolph- thalein indicator to the bottle of commercial formaldehyde and then adding ,bo n caustic soda solution until a faint pern.anent pink colour is obtained. Making tiik Tkst. Af,.!"*!?'''''''''?',"''' ^'''•' ^'•*'.^«'^^"<' " r..presentative portion of the milk to be tested After thoroughly pounng th,s portion, t.ke a san.,.lo witli the ]0..'5 c.e. pipette nd deliver the sample mto a white ,lelf eup or beaker. Add about 1 c.e. o m ieato, 1 per cent solution) and add the alkaline .solution as in testin, for aeid ty U a de.Mded permanent jiink cojonr is obtaine.l. Now add ^' ec of the ne.tr;! f , hy.le solutio,. whieh destroys the pink eolour in the snn.lc The burette ;„f'''"fl^;^^^ to the mark with the alkaline solution, aft.r whieh thl^tdut^ £ S h " So he cup or beaker unt.1 a pern.anent pink eolour, of the same shade as in the fi^ t operation, is obtained. The number of eubie centimetres of solution used Tn 1 e se..,.„. operation is noted and will represent the per cent of casein in the , ilk Fo e-xampe ,f ■>. c.c. of solution are use.l. the percent of casein in the milk i 1^5 bottle t''! t".""f ■'"''•"'','"'"""" ^'""^''^ '"^ '^"'^"t preferably in a plass-stoppered bottle. In tnno the a.nt pink colour of the formaldehyde solution will dislpe'r owmj; to the action of the .-arbonic aci.l of tlie air, when a few drons of tl.n u T solution should again be added to the formaldehyde tl res^;; t'^olou " I sing slightly more than 2 c.c. of formaldehyde solution in making the test wil' not in any w.iy affect the results. " ' ^^'" In case a 16-3 c.e. pipette is not obtainable, the 10 c.c. pinette m,v be „».,] ,„ i the te,t performed as outlined. The number of cubic ocntim'trefof " utionT .ir" in the second neutrahzat.on must be multiplied by the factor 1.63 to give the pe n of casein when the 10 c.c. pipette is used. '^ 16 To avoid the necessity of this mnltiplioMtion for rnnh 8nmpl« tcslpd when usinff the 10 o.c. pipette, the following tnble has heen pn.p„mi by the oriRinntor of the test •*"" ;ilkiili iiM-(). 1-00 I'On no 1'15 f20 f25 1-30 •it wilt cawin 1T,3 ITl 1-7!) 1-87 f9.1 2-04 2-:2 (| »lku]i iiHt'd. 1-36 f40 1'4B 1-BO 1-S6 I'SO I't-r ci'iit ciiw'iii 2-20 2-28 2MG 2-44 2Ti3 2-61 DETERMINATION OF THE PER CENT OF CASEIN IN MILK BY MEANS OF THE HART CASEIN TEST. The apparatus employed in determining the per ^- '*"^'— ' "-"k- """« - on the i. trf-jit.. Jiwllfc «r ^;. FK. S. :rh. apparatus (Ki^. :,) used in making a moisture determination, consists of: (a) The scales; (!« become, o.ly, > i. difficult to get duplicate tests to agj" "^^ Af*»ciNO the Test. ,H l"i^"''i"v " T- '^^- '"^- '" ''1''*^'' '^^ '"""P'^ >« ^^«^ should be ne^..*lv ^I„n r J ^ . * -^^ •' ""'""■" "^"''^'^ '"'"■ "«' alcoiiol lamp t„ drv it fhorouyhK oj^^ placed on the pan of the ^.le. After the c^ is cool. theLle isMLre^ j'idiu^t 10 •K the woiKht on the tare beum. Ton Rrann of butter are weighed into the cup from U.e 8«,„ple .., the jar 1 h« cup in now heated .lowly over the lamp to eva,«rHto the T 1m I. •* '^P"''^-. ^^^ *'^''*'"» •''""''I P'"*"^** •'"^''y "o »» not to char the fat. and while being heated the butter should be agitated by shaking the cup with a rotary motion. Care must be taken that no fat is splashed out of the cup The evaporation will be accompanied with more or Ws noise from the sample. As soon as th,. Moiso reasos and just as the butt-T pomr.i.-n.v. t.. tak.. „„ „ more uimIht .-olour. tnc h.u ing should bo discontinued, as all the water will have been evaporated. Should the heating !«. .■ontinue.l beyond this point, the re-idue will Ih> ..hurnd aiul the result ot tho tcs will be too high As soon as the heating is concluded, the cup is placed on the scale pan and allowed to cool. Tho scale does not balance now since the sample H i^'hter. ou'.n^' to the ovaporntio.i of the water. The weights on the b.uni an- now tS henm'" balances exactly and the percentage of water is read from When the hot eup is j.la-od on the scale pan, an upward current of nir is set up. duo to the cup healing the surrounding air. This upward current of air tends to raise he scale pan Consequently, if the reading is taken while tho cup is still hot. It will be too high, since the weights must be moved farther over on tho beam to counteract the effect of the air current. The high pressure oven described under the " Determination of the Per Cent of Water in Cheese furnishes a most satisfactory method of evaporating the water irom the sample of butter. A method of heating the sample by using a paraflSne bath has also been advo- cated and widely used. The cup containing the butte. to be heated is placed in a second cup which is surrounded by paraffine. A small copper kettle contains the paraffine which ,s boated to a temperature of 175° C. (847° F.) which temperature 18 inaintained during a period of five to seven minutes. This method avoids danger ot over-heating the sample, but lengthens the time required to make the' test. E.x..eri- ence has shown that heating direetly ever the lamp, when ..arofullv done is quite accurate as compared with chemical analysis. As with cream testing scales, the scales used for the testing of butter should be kept in a dry place. DETERMINATION OF THE PER CENT OF SALT IN BUTTER. H.t«3°""''^^'* °^ ''*'*"" ;'"* '> ^' '^^"' "^ *"'' '" ''""«' »* somewhat similar to determining the per cent of acidity in milk and cream .»!. A '"f^'""^ •"/ •^«'^'™'"'"» tl"" silt content of butter is based on the fact that salt and silver nitrate neutralize each other in definite proportions. The salt con- !nTnf t'" f definite quantity of butter is washed out and dissolved in a definite quantity of water. A definite volume of the salt solution thus obtained is measured out by means of a pipette and the salt in it neutralized by titrating with a silver nitrate solu ion of known strength, using a potassium chromate solution as an indi- cator, to determine when the neutral point is reached. Pipettes of diffnrent volumes have been recommended for measuring the salt solution and correspondingly different strengths of silver nitrate solutions. Of the Ci^c^W^ if'/T'n^-'^"-'""'!;!^'""'^ *"'^'' '^^ suggested, that outlined in S S ♦ ^' F»'^«">ty °f Wisconsin by J. L. Sammis. seems to be the most adapted to our conditions. In this method, a silver nitrate solution, prepared by h nnir^' A%T "l""*""^ /^-^^ ^'■"'"' "^ chemically pure silver nitrate in two sohitinn 'r A u !^ '^l^^'-f-s -^ 'li^till«l water, and a potassium chromate chrorTt'e h,T ♦ fi ^'^^"ving seven and one-qnarter (7-2.5) grams of potassium chromate in twenty-five (25) cubic centimetres of distilled water are u=ed w Phkpamtiom or tiir Mii.vk> Nitiim S..llti»x. procured from any .ood dru7hJ«, xl ■ . "1 potaiiium chromate may be W cubic SiSri^l, taw'" ""^ i° '""'"1 "'"' '"••"'•"' '» «•• l"'«J'^ .oule and U I wShi on to Z n "'''«'""""« ''i" ^ squired to balance the place oneTthehtvier ic^.hU u/ed in ^'T""f, '" *'''«'' " -•"""•« »^ ^""-' «"' per cent n-,t<.h of^h^LZ \T1ZZ '''' u' ^^ "T "^ '""''"""' "" ••'" '^o pn- and ad"'" -own paper and kcp °n u d rk h ,u d "'tI, ' "''" "'' '" "■'*' "" """"""••' "' to protect the silver nitrut' crystals Zli.h^n'''"'''' ^'T'T ^'""''^ *"-' »='''^'« solutiof. it is advisable for 7}l t ^ """'' '° '^^ ^'^'''■' "^ ^i^f'" "" the that five an,l one" nth ^l^l^Z^ k""" -"."i""!*^ f ^'" "^ ''^""' ""'"'"^ - nnd tifty (250) cubic centimetre; o 2t " "''lif "''• /^'I'^l' «•'" "'"k«> two l„„„lrod fr«,uentiynni there w^ttT li^^r JJ^,: ■';::"::;i:" ♦'- '^^ -"'^ ■'-^ Preparation ok Potassmm Ciihomatk Soli t.o.v. .eveJIiLfrS't:?'?^^ Sm"':;;r'"^^' ^'? "^°^^- '^ ^-"--^ ^^ Bppliancpi riH|uirt> imhos hiirh, ifniduiitwl to hold two hundn>d and fifty (250) cubic ct-ritlinvtri-i; (c) A 170 c.c. pipette; id) a RmaU ghiis breaker; (e) a ten (10) cubie centiniptre burette witli ii\a*-> utop-eoek irmduiited to one-tenth (Mii) of one (1) rubic ocntinictrc-' and chinip for liolding the burette; (/) a dropi)er bottle for the potaiwium rhromnto indioator; (.'/) a one-pint wide nioutli gh** Uittle, Making tiik Teht. A sample of butter is sociir.!.! anaker. To the salt solution in the Iteaker is added one drop of the potassium chromate soluti.-.i from the dropper bottle. The burette is fillcl to the top of the scale with tlie silver nitrate solution, care bcinR taken that no air bubble, remain in the tip of tlic burette The silver nitrate solution is now slowly dropped from the burette into the beaker, which is shaken constantly to mix the silver nitrate solution with the suit solution \s soon as a permanent faint reddish-brown ••olour is obtained, the addition of the silver nitrate solution sliouhl case as the salt is all neutralized. Th.. number of cubic centimetres of silver nitrate solution reciuiri'd to iieutrali/e the salt is read from the burette. Each cubic centimetre of solution usod rcpn-sonts one p.T .•cut of salt in the butter. Thus if two and nine-tenths (i>.9) cubic centimetres of solution arc u.scd, the butter contains two and nine-tenths (2.9) per cent of salt. Nearly all well wat.Ts contain more or less salt and for this reason are not suitable for use in making the silver nitrate solution. Condensed steam from a boiler also contains impurities which render it unfit for use for this purpose. Clean rain water will ^ive more satisfactory results than either well water or condensed steam from a boiler. If well water is used to remove the salt from the butt.r in making the test it should be tested for salt in the same manner as the salt solution from the butter is tested. Whatever perceiitatfo of salt is present in the well water should lie dclucted from the result of the test of the butter. For example, if the well water shows 0.5 in-r cent of salt and the butter shows .T ,--, per rent of salt, the correct test of the butter is 3-5 — 0.5 per cent = 3.0 per cent since 0-5 per cent of salt has been added with the water. Condensed steam from a boiler shoul.l not be used at all in making the test. \\cll water to be mixed with the sample of butter siiould not even be heate« reading must bo multiplicl by'", i'," • r ,;:;' fT '" ;"'./'^-'"""' b-.ttlc. the ha. boon u«cd in a 10 ,M.r .^-nt mUk bo fl , i- ' "'"' 'f " ^-^ '^''"" «'""•''« that i*. the i^r cent of fnt ; XnT, ..I v , I . """'^'7 ""''.' ^ ""■I'ipli'-"! kv 4; gramn for which th,. bo Uc i. ".I n 't "^ '">' tij.Iy.n^ tho reading by the nun.bcr of gran., u.ed in nmking the i;,;"""*""-""' "'"' <''^"l"'*r the rc.ult by ,1... n,,,..,,.,^ of Dkte..m,nat.on o. t.,k IV:,, c,nt of Wateu ,n Ckme If 8tonm "n.icr prc4 1h r " i , ' "'T •'™.' /'°"' '^e loM i„ wci«h,. f-r cn„t of n,oi!tur. i^ IL"!" '•!''u:."l^"'^"' «atKsf„cto_,y n.ethod of dCcrnu.ung the ocr cn„t of n-oi^turc ^n ^.^^ e h by Irlrlh 'f '7 ""'^'"' "' d^'ernu.ung ntisi, IS Dy means of tho liigh pressure oven (Fig. 0) 3- ^i;"s^s:— -j-^--,--.^ ™ £..^ 93 wall, and a„ outlet to .Jniin of! .),« ron.|pn.wl w.itBr. The rhiirober ii fittixl with a perloMlcU rack on wh..h to plm-t' th« •nmplM and whi.-h permit. fre«. circulntion of the warm air oround the lamplri. The ovin ii fitt.d with a • !o.o-attitiir door .,nd a thermometer extendiiiR into the phamber. The tempt-nitur,- m.iintaiiiP.| in the oven may be reirulated by the itcnni pre«.iro appli»l in the hollow walU. In ttddillon to the o»en, a fine balance i* nocewnry or n good moi.tur.- » ■"*«'« with n 10-Bram inmplo. a rondintf of 38^8 per c-nt of moi.tur., miiy be taken, but with a Toriion toule only 30 por cent may be road without the ixtra ttram weighta. SIakino the Tut. determ.nut.on. The anrnple i. thoroughly ipreud out by moan, of « knife nnd t.h.to -hch h«. been thorouBliIy dried by heating and then bulan-.-.l on the *.-..le . t ' cooling. The cheew la .preiid iii. thinly and an evenly .„ poMibie over the di.h Tlie work of •ampl.ng. pulverizing and weighing the ehee«. into the .ii.h »hould W- done at quickly a» powible. to avoid lo.. of water by evaporation. The di*h containing the Bonft t?»r '''«"-^^"' »»"• °^«'"- t!"" 'Jo'-r eh..ed. and 45 to .',0 pound, .team pre.,ure applied to the oven. fhi. should give a teni|KTnturo of 22:,^ K. to S.'.O" F whi.-l, ,vlll be«uffi.,entl.vi.igh. The sample in lieaU.! until all tl... waf.-r ha. UviiVv™"'.! which point IH dcterminwl by .uoee.sive weighings followed by further heating in' the oven of course aUowiiig the .ample to cool before weighing ..a.li time When the .ample cease, to oso weight, the water h all evaporated and the iK>r cent of moi.ture ,. dctermine.1 from the 1o,h in weight. The gnimn of moinure evaporated multiplied by 10 will give the per ..ent of moisture. For example, if the ]0 gr^,n of chee.e lose 3.6 gram, of water from evaporation. 100 «r,.n.8 would lo.e 1m„ divided by 10 and multiplie.1 by a..'.. whi
  • 8tatteaai aU> Ooadaaaed KUk aad CHtr Flaafa, ate., la Oaaada. Okaaaa Faaterr aad OraaatOTT^PUata wltk 0»aeUaat!«aa. Tka JhSrr ladaatry^Aot, 1014, aad Ba«rfatliM. Tka Oold 0torasa Aet, 1007, aa Aataadad la 1000, and Baaalatloaa. Tka Oold 0toraaa of Food Frodaete wltk aoMO aotaa oa la- aalatloa aad Warakoaao Maaaseaiaat. <]IB01TLABS. Tko mik Taat A«t. Tko Oatlook for Oaaadlaa Tomatoaa la Oraat Brltala. Oraaiary Oold Sterac* Boaaaaa. Botaa oa Ooar Tastlas. Bavlaad Uat of A*pla Daalara la Xortkara Oatarlo, Maal- teka, 0aakataka«aa aad Alkarta. Tka Braadla« of Dairj Batter. _ . . ._ ^. iliOFroeooUas aad 8terace of Fralt for tko Ooautorelal of 1016. Oaaaaa of Tarlatloa 0oparater Oraam. Okarrr Praeoollac PoadlUltlaa. Oow Toattac Botaa. la tka Feraaataca of Fat la Haad 0FBOIAI. FUBUOATIOira. Kap akowlaa tko Loeatloa of Okeeae Faetorloa aad Oroaai- ^ j|0g fa Oaaada. Bapert of tka Tklrd Domlaloa Ooaf araaaa of Dairy Baporta, Daaemkar 6 aad 7, 1011. Aay of 4k»— paUloatleaa will k« leat froa of ekargo oa appllaatloa te tko Sairr aad Oold Oteraxa Ooaudaaloaar, Ottewa, Oat. ^^7i aSloteat aamSor of kaUatlaa 0O, 80 aad 88 aad alrealar 14 arlll ka saat «• tka maaaaer of aay ekaaao f aetorr or eroaaorjr te aapply oaa te eaek patroa. Boa. 3^88 aad 40 ralatiac te tka fmlt (rowlac ladaatry kara kaoa traaa- f arrad te tk» Fralt Oeaualaateaar'a Braaek.