BULLETIN 167.] IOCTOBER, 1908. 



Ontario Department of Agriculture. 



DAIRY BRANCH. 



LIBRARY 

 NEW YOR K 



BOTANICAL 



Mitchell- Walker Moisture Test aARDEN 



By J. W. Mitchell, B.A., Supt. Eastern Dairy School, and 

 W. O. Walker, M.A., Lecturer on Dairy Chemistry, Eastern Dairy 



School. 



In October we began work on the problem of rapid moisture deter- 

 mination in dairy products. Owing- to the increasing- demand, of late 

 years, for a practical moisture test to be used in creameries and cheese 

 factories, not a few methods have appeared attempting to meet this 

 demand. We examined the reports of others upon the various moisture 

 tests that are on the market, and in addition fully investigated a num- 

 ber of them ourselves. We concluded that the only feasible methods 

 were the beaker method and Gray's test. The beaker method consists 

 in weighing accurately into an aluminum cup a small quantity of butter, 

 heating it over an alcohol flame till the moisture is all driven off, allow- 

 ing to cool and reweighing. The loss in weight represents the moisture. 

 From this the percentage of moisture in the sample is calculated. We 

 found some undesirable features connected with this method, viz., 



(i) The necessity of having a very sensitive balance with attached 

 weights, or else having a cheaper balance with separate weights which 

 are rather tedious to use and liable to get lost in practical work in 

 factories. 



(2) The necessity of calculating from the weights obtained the per- 

 centage of moisture in the sample. 



(3) The uncertainty as to the right moment to stop the heating. 



(4) The care required to prevent loss by foaming or spattering. 



(5) The uncertainty as to the rip-ht time to reweigh after heating, 

 since if reweighed when still warm a wrong result is obtained, and if 

 allowed to stand too long in the open air before reweighing the dried 

 sample absorbs moisture from the air, and hence again a wrong result 

 is obtained. 



(6) The necessity of weighing accurately to the second decimal 

 place, in grams, to give a sufficiently accurate result. 



