86 



2. Addition of water to milk makes milk appear richer, for the 

 greater consistency of pure milk prevents the easy formation of 

 cream. 



3. The cream rises quicker or slower according to the tempera- 

 ture at which the milk is kept. Moreover, the layer of cream 

 appears larger at lower, and smaller at higher temperatures. 



4. Milk frequently sours, and therefore coagulates before the 

 cream has all risen. 



5. The manner of transporting the milk influences the process 

 of creaming considerably. 



6. The cream constantly varies in percentage of fat. Often it is 

 very rich, then again thinner; sometimes it collects and rises 

 easily, and at other times less completely. 



For comparative quantitative fat determinations, it is advisable 

 to use, in the place of the costly creamometer, the simpler and 

 cheaper apparatus of Schatzmann (to be obtained through the 

 " Schweizer Molkerei Yersuchsstation, at Lausanne "). 



The points mentioned above do not influence the results, which 

 may be obtained by means of the improved lactobutyrometric test, 

 whereby the percentage of fat can be determined in milk in from 

 one-half to one hour's time, sufficiently exact, while with Chevalier's 

 creamometer, we are obliged to wait 24 hours before the very 

 unexact results can be obtained. 



The results obtainable by the lactobutyrometer are not so exact 

 as those which are obtained by a careful chemical analysis, but suf- 

 ficiently accurate for the purpose, differing from the truth in the 

 average not more than 0.2 to 0.3 per cent. Small errors do not, 

 however, influence the usefulness of the test, if we consider the 

 value arising from a quick determination of the fat. 



The following apparatus are required for the application of 

 this test : 



1. Glass rods for stirring the milk. 



2. A water bath to prepare water of 40° C, consisting of a high 

 cylinder of metal, which rests on a dish upon which alcohol may be 

 poured and ignited, to heat the water to the required temperature. 



3. A glass or metallic cylinder for the water of 20° C. 



4. A Centigrade thermometer. 



5. A drop glass for potash solution. 



6. 3 bottles, one containing ordinary alcohol for burning, another 

 alcohol of 90 to 92° Tr., and the third ether. 



