DAIRY CONFERENCE.

Manawatu Standard, Volume XL, Issue 7067, 29 July 1901, Page 4

DAIRY CONFERENCE.

The following papeis were read at the Dairy Conference:—' :

MILK-TESTING.

[By WvM. Sinqieton, Dairy Instructor]

Until the year.lßso, wlien. the factory system of cheese-manufacture developed, the subject of milk-testing had little attention;^ -.This new developnent,"accompanied a 'few'years later by a similar one,iii 'butter, made it necessary to have 'some metliM of testing milk, particularly as to its. fat contents.:: Since that: time different chemists have endeavoured to give ■thepublic a test which would, be accurate? simple and cheap, but'all tests devised seemed to' come shdrt in one or more points until, in 1890, Dr Babcbck introduced his'famous test, which lias since given such universal satisfaction.' Since :the introduction of this test a largej number:" of different styles of machines have been placed on tho market.; In getting a machine it-is important to select.one that is. durable,..and will- run ..smoothly -whether loaded or empty. If you are selecting a turbine, do not have the jet "of steam striking near your bottles, and have a hole in the centre of the cover large enough, to per-' mitthe'proper circulation of air. See that the pockets are not easily detached, and that when the machine is running, the-'bottles- pan assume- a perfectly horizontalposition, and a perpendicular one when'at rest. • . :-. ■ ■ .''

;It is very important to have the bottles properly graduated..,' They ■ may be calibrated, by using either mercury or water, or a still simpler method is to test one sample of milk with the different ;bottles, and then discard those"that are so milch as one-tenth astray. . The,accuracy of a milk-test depends principally -on the sampling. Unless .the operator, gots a fair, average sample ■he may just as well approximate :the percentages as to run the test through and get misleading results.. In order to get a true sample-the milk sliould.be poured from one vessel to another. However, when milk is drawn to a factory, the agitation it gets on the way and the subsequent pouring into the weigh-oan generally makes a thorough mixture.

As a rule, in ordinary factory work the ounce dipper is sufficiently accurate, and is most convenient for taking composite samples. Each morning, a sample of milk is taken and put in a bottle containing some preservative. The most common preservatives now in use are bichromate of potash and corrosive sublimate, and only enough of either ofthese substances to keep the sample from thickening should be used. The sample-bottles should be kept plainly labled or numbered, well covered and in a dai-K place. In preparing the sample for testing the same care must be exercised as when the sample was taken for the composite-jar. No cream should be allowed to adhere to the sides of the bottle, nor any lumps show in the mixture. Before taking the sample the pipette should be rinsed with the milk that is to be tested. When delivering the milk to the bottle, place the end of the pipette against the side of the neck and gradually release the prcsure. Be sure to let the pipette deliver the milk slowly enough to permit the air to escape without taking any of the milk with- it. The last few drops should be blown out of the pipette into the test-bottle as it is important that all milk should be delivered from the pipette to the bottle.

The acid should be kept in a cool place. JN ever place it near your boiler or where the sun's rays will strike itbulphunoacid has a great affinity for water, and should, therefore, be kept covered to exclude the moisture of the air, as this will shortly weaken its strength. It has been found that acid with a specific gravity of TB2 to TB3. and a temperature of from 60deg to 70 deg. Fahr., for both acid and milk gives the best results. 175 c.c. of this acid is added to the test-bottle, care being taken, to-hold the bottle in a slanting position, so the acid may follow, the glass rather than drop through the milk Small variations in the strength of the acid may be counteracted by varying the quantity somewhat.: In adding the acid, all the milk should be washed down the neck of the bottle. To facilitate the mixture of the acid and milk the bottle should be given a rotary motion, but no milk should be allowed toget into the neck. As soon as the curdy matter is all dissolved the bottles should be placed in the centrifuge and whirled. By no means should the bottles be allowed to cool before whriine, unless the-temperature is again raised" before the operation takes place. After whirling five minutes, the centrifuge is stopped, and hot water added until the bottles are filled to the base of the necks They are again whirled two minutes when hot water is again added, filling the bottles to the 9-per-cent. mark • After this they get a final whirling of one mimite to bring all the/separated fat into the neck- of tho bottle. It is very essential-that the proper speed be maintamed throughout each of these whirlings. ■. ■ . ■. ■ In reading the fat-column, the bottle must be held in an upright position, and the reading taken from the highest to tho lowest fat,limits.: These readings should, be taken in a room whero the temperature is about 70 deg., Fahr., and be read as quiokly and accurately as possible. If the room is much bolder or if many bottles are to be read, the bottles should be placec" in a hot-water bath until the readings are taken. The temperature of the, fat at this stage should be about 130 dog. Fahr. .; The cleaning of the glassware is an importanfrpoint in connection with the testing of milk, and unless this point has proper attention, aocurate results cannot be obtained. The test-bottles should be emptied as" soon as the tests are recorded. This prevents the fat from hardening on the neok of the bottles, and the principal part is washed out with the hot liquid. The sample-jars should never be emptied until after the readings have been taken and found satis--factory. As soon as emptied the bottles should be rinsed with warm water, arid washed -..with some alkaline solution After this they should"~"be rinsed with hot water until they are clean and bright.. :