722 



EXPERIMENT STATION RECORD. 



differing widely in the amount of solids-not-iat over 70 per cent of the results 

 obtained have been in the opposite direction. 



"A possible expLinatiou maybe found in changes in the relative proportions of 

 sugar and casein in milk. For the reason that a given amount of milk sugar 

 increases the specific gravity of milk serum more than an equal amount of casein, it 

 follows that a factor expressing the relation between specific gravity and solids in 

 milk, of average composition, would not apply to milks where the ratio of casein to 

 sugar dift'ers from the aA^erage. In the above formula the factor 2.5 is for this reason 

 a trifle too large for milk containing more than the average amount of sugar, 

 compared to casein, and too small when the opposite is true." 



The results by this formula are compared with those by the formula 

 of Hehner and Eichmoud' and by Richmond's^ new formula. 



"Any of the 3 formulas mentioned in this paper will, in most cases, give satisfactory 

 results for solids, especially as the error falls entirely upon the solids-not-fat where 

 it is of comparatively little importance." 



Tables are given i^repared from the author's amended formula show- 

 ing the per cent of solidsuot-fat corresponding to lactometer readings 

 from 26 to 36 and fat content from to 6 per cent. 



"An inspection of this table shows that the percentage of solids increases practi- 

 cally at the rate of 0.25 for each lactometer degree and 0.02 for each 0.1 per cent of 

 fat. This relation is expressed by the simple formula: 



Solids-not-fat =i L+ 0.2 f and 

 Total solids = J L + 1.2 f. 

 in which L = Queveune lactometer reading and f:= percentage of fat. . . . 



"It gives results which differ not more than 0.04 from those of the complete for- 

 mula for milks containing up to 6 per cent of fat, and has the advantage that it can 

 be easily and quickly applied without tables." 



Notes on pasteurization of milk and cream, H. L. Russell 

 and F. W. Woll i^Yisco7lsi)l Sta. BpL 1895, pp. 158-173, pL 1).— Bac- 

 teriological investigations, H. L. Russell, (pp. 158-164). — Bacteriolog- 

 ical studies were made of the milk and cream pasteurized in the appa- 

 ratus described in Bulletin 44 of the station (E. S. R., 7, p. 087). A 

 brief summarj^ of the results is given in the following table: 



Nnmhcr of bacteria per cuhic ecntimeter in milk and cream. 



1 Whole milk.—ED. 



" The cream either in the pasteurized or raw condition is invariably richer in bac- 

 teria than the milk. This is particularly true in the case of the uupa.steurized 

 material. The cultures made from pasteurized milk often contained so few bacteria 

 that it may be said to be almost sterile. In 40 i>er cent of samples examined the 



1 Analyst, 13, p. 26. 



-U. S. Dept, Agr., Division of Chemistry Bui. 43, p. 181 (E. S. R., 6, p. 614). 



