112 EXPEEIMENT STATION RECORD. 



A comparative study of this uietliocl aud tlie sodium carbonate aqueous ex- 

 traction method was made, utilizing various Iciuds of material. It showed that 

 the alcohol method gave lower but satisfactory aud comparable results, and it 

 made no difference whether the extract was analyzed immediately or after 

 standing for some time. 



The authors point out that in order to obtain true and concordant results 

 with the sodium carbonate method careful attention must be given to some of 

 the details of manipulation, as, for instance, " after neutralizing the sodium 

 carbonate by clarifying with alum or lead, the work must be carried on with 

 dispatch as the enzyms again become active; the acidity of the sample must be , 

 determined and the quantity of sodium carbonate thereby regulated, or the 

 accuracy of the results will probably be affected; normal lead acetate should be 

 used instead of alum for clarification under most circumstances, otherwise au 

 error is introduced." 



The authors express the opinion that the alcohol method is to be given the 

 preference for general sugar work, but that where a long series of comparable 

 results are necessary the sodium carbonate aqueous method may sometimes be 

 usetl to advantage. 



The estimation of total solids in milk by the use of formulas, R. H. Shaw 

 and C. H. Eckles (U. 8. Dept. Agr., Bur. Anim. Indus. Bui. 134- PP. 31, fig. 1). — 

 This work forms a part of investigations concerning milk which are in progress 

 in cooperation with the Missouri Station. It was carried out for the purpose 

 of testing the accuracy of various formulas in common use (Babcock's, Rich- 

 mond's, and Fleischmann's) for determining the total solids in milk, and to 

 determine whether an improvement could not be made in the way of obtaining 

 an easy, accurate method for determining the specific gravity of milk for the 

 use of such men as usually have charge of ofhcial testing. 



With the above objects in view, the authors compared the percentages of 

 total solids calculated by means of formulas aud of total solids found by the 

 gravimetric method. They further compared the formula whose results came 

 closest to the gravimetric figures, under very exacting conditions, and finally 

 sought to modify the existing, or devise a new, lactometer for determining 

 the specific gravity accurately. The fat and total solids in this work were 

 determined by the Babcock asbestos method, while the specific gravity was 

 determined with the Westphal balance at 15° C. 



From the work the authors conclude : 



" For purposes where exact percentages of total solids are demanded, the use 

 of any formula will not fulfill the requirements. 



"Of the formulas in general use, that known as the Babcock (revised) 

 formula gave results closest to those obtained gravimetrically. In 430 com- 

 posite samples analyzed for total solids 2.5G, or nearly 60 per cent, when calcu- 

 lated with this formula agreed within 0.25 per cent of the figures obtained 

 gravimetrically, and 389, or over 00 per cent, agreed within 0.50 per cent. In 

 another test with 84 samples of milk obtained from four individual cows under 

 oflBcial testing conditions, determinations made on each milking showed that 

 the total solids calculated by the formula in 53 cases, or G3 per cent of the 

 total, agreed within 0.25 per cent of the gravimetrically determined figures; 

 and in 78 cases, or 93 per cent of the total, they agreed within 0.50 per cent', 



" Neither individuality nor breed in the cows seemed to exert any notable 

 influence upon the application of the formulas. 



" The Babcock formula may be safely used with normal milk where only 

 comparatively close approximations are required. It must be left to the deci- 

 sion of those in need of such figures as to whether or not the formula will 

 fulfill their particular requirement. 



