1902.] PUBLIC DOCUMENT — No. 33. 159 



All glassware found to be correct is marked "Mass. Ex. 

 St.," by means of a sand blast, working under twenty-five 

 pound pressure. The necessary air pressure for the blast is 

 obtained by a double-acting power air pump, * with a thirty- 

 gallon reservoir. 



It became necessary at first to test the ware in use by all 

 creameries and milk depots. Now, practically none is 

 received from these sources, but rather from the large 

 supply houses, who furnish tested ware whenever requested. 

 There has been examined to date 5,041 pieces, of which 291 

 pieces, or 5.77 per cent., have been found to be incorrect. 

 One order from a large supply house, numbering 441 pieces, 

 contained 149 pieces, or 33.8 per cent., incorrectly gradu- 

 ated. The wisdom, therefore, of this section of the law is 

 apparent without further argument. 



Manufacturers are now inclined to be more careful con- 

 cerning the quality and accuracy of glassware supplied, for 

 the reason that a large part is examined by the several 

 experiment stations before coming into the hands of the 

 users. 



Examination of Candidates, f — It seemed wise to require 

 candidates to present themselves at the station laboratory 

 for examination. In all, 45 candidates have been examined 

 to date. Scarcely any were found to be free from faults, 

 but the larger number appeared to understand the general 

 principles of manipulation. A few were noticeably careless, 

 and had but an imperfect understanding of the process. 

 As much instruction as possible was given in the time at 

 our disposal, an especial effort being made to correct the 

 serious faults. In furtherance of this idea, the following 

 circular concerning the points especially to be observed in 

 making the test was printed, and a copy given to each party 

 examined : — 



1. Milk or cream should be carefully and thoroughly mixed, — 

 never by shaking the sample, but by gently rotating it and by 

 pouring from one vessel to another. All cream adhering to the 



* No. 3, A. Babcock & Bishop Company, New York. 



t The inspection of the glassware and the examination of candidates were largely 

 in charge of Mr. E. B. Holland, who gave these matters very careful attention. 



