. Analysis of milk and milk products. ingoperations in an atmosphere of hydrogen. Werner-Schmid Method.—This is a very satisfac-tory and rapid method for the determination of fat and isespecially suitable for sour milk. Ten c. c. of the milk are measured into a long test-tube of50 c. c. capacity, graduated to tenthsc. c, and 10 c. c. of strong hydro-chloric acid added, or the milk may beweighed in a small beaker and washedinto the tube with the acid. Aftermixing, the liquid is boiled one and ahalf minutes, or the tube may becorked and heated in the water bathfrom five to ten minutes, until the
. Analysis of milk and milk products. ingoperations in an atmosphere of hydrogen. Werner-Schmid Method.—This is a very satisfac-tory and rapid method for the determination of fat and isespecially suitable for sour milk. Ten c. c. of the milk are measured into a long test-tube of50 c. c. capacity, graduated to tenthsc. c, and 10 c. c. of strong hydro-chloric acid added, or the milk may beweighed in a small beaker and washedinto the tube with the acid. Aftermixing, the liquid is boiled one and ahalf minutes, or the tube may becorked and heated in the water bathfrom five to ten minutes, until theliquid turns dark brown. It mustnot be allowed to turn black. Thetube and contents are cooled inwater, 30 c. c. of well-washed etheradded, shaken, arid allowed to standuntil the line of acid and ether is dis-tinct. The cork is taken out, and adouble-tube arrangement, like that of ^ the ordinary wash-bottle, stopper of this should be of cork and not of rubber,since it is difficult to slide the glass tube in rubber, andc. 2 6 ANALYTIC PROCESSES. there is a possibility, also, of the ether acting on the rubberand dissolving it. The lower end of the exit-tube is ad-justed so as to rest immediately above the junction of thetwo liquids. The ethereal solution of the fat is then blownout and received in a weighed flask. Two more portionsof ether, 10 c. c. each, are shaken with the acid liquid,blown out, and added to the first. The ether is then dis-tilled off, and the fat dried and weighed as above. Leffmann-Beam Method.—Among the processes forthe rapid determination of fat those employing centrifugalmachines have been most satisfactory. The followingmethod can be applied very cheaply, both as regards theoriginal cost of the apparatus and of the chemicals requiredfor the test, the latter being usually no inconsiderable itemwhen many tests are made. The manipulation is verysimple. Machines arranged for either two, four, six, eight, ortwelve bottles are manufactured. The
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