590 TRANSACTIONS OF SUB-SECTION B. 



Propagation of Errors. — The error of solids not fat is found from the above 

 data, and the formula R J = r, a + r 2 3 . . . to be : — 



By total solids ± - 077 per cent, solids not fat 



By lactometer 1° = 1 mm. ± - 5 „ „ „ 



By „ 1° = 1 cm. ± 0-045 „ 



The method was next applied to that part of the inaugural dissertation of 

 J. H. Hinchcliff which attempts to measure the difference between calculated and 

 found total solids. The error of such a difference is about ± 0.13, whilst nearly 

 one-half of the observations fall within those limits. There is therefore no 

 evidence that the use of the formula for calculating the total solids of the milk 

 of one cow or one milking will not give close results. When the average of several 

 milkings is taken the error is reduced, and the conclusions based on such averages 

 are justified. 



