562 Miss Fraser and Mr. Gardner. Origin and [June 17, 



Table III. 



Method. 



Weight 

 of fat. 



Weight 

 of chole- 

 sterol 

 added. 



Weight 

 of com- 

 pound. 



Weight 

 of chole- 

 sterol 

 (found). 



Weight 

 of chole- 

 sterol 

 in fat 

 (0 -113 



per 

 cent.). 



Weight 

 of chole- 

 sterol 

 less 

 chole- 

 sterol 

 in fat. 



Error. 



Direct precipitation — 

 Weighings in filter paper 

 )) )> ») 



n >» 



Saponification — • 

 Weighings in filter paper 



0 -3064 

 0 -3032 

 0 -3090 



0 -3097 



0 -0491 

 0 -1060 

 0 -0242 



0 -0555 



0 -2014 

 0 -4646 

 0 -1060 



0 -2210 



0 -0489 

 0 -1129 

 0 -0258 



0 -0537 



0-0003 

 0 -0003 

 0 -0003 



0-0003 



0 0486 

 0-1126 

 0 -0255 



0 -0534 



-0-0005 

 4-0-0069 

 -f 0 -0013 



-0 -0021 



IV. In the material one wishes to analyse cholesterol may be present 

 both free and combined, and it was therefore necessary to test the accuracy 

 of the method as applied to the estimation of pure specimens of esters of 

 cholesterol when in the ]?resence of comparatively large quantities of some 

 substance other than cholesterol, which has to be removed by washing or 

 saponification. For these experiments we used known weights of cholesterol 

 oleate and cholesterol acetate in weighed quantities of fat (beef suet) purified 

 by melting and filtering through glass wool, the process being repeated 

 until the fat was clear. Separate analysis of the fat gave a percentage of 

 total cholesterol of 0-07. The results are given in Table IV — 



Table IV. 



Method. 



Weight 

 of fat. 



Weight 

 of ester. 



Weight 

 of chole- 

 sterol 

 in ester. 



Weight 

 of com- 

 pound. 



Weight 

 of chole- 

 sterol 

 (found). 



Weiglit of 

 clioleslerol 



in fat 

 (0 -07 per 



cent.) . 



Weight of 

 cholesterol 



less 

 amount in 



fat. 



Error. 



Saponification — 

 Weigliings in filter paper 



it a )t 



0 -7030 

 0 -4516 



0-1178 

 (oleate) 

 0 -1812 

 (acetate) 



0 -0699 

 0 -1634 



0 -2772 

 0 -6412 



0 -0673 

 0 -1558 



0 -0005 

 0-0003 



0 -0668 

 0 -1555 



-0-0031 

 -0 0079 



From these results it is clear that, with the quantities of blood used in the 

 experiments described below, the metliod is sufficiently accurate to give 

 reliable information as to th(! variation of the percentage of cholesterol and 

 cholesterol (jsters in blood under various dietetic conditions. 



Though the errors of experiment will be relatively greater the smaller the 

 quantity of material used, we believe that dependable results can, with care, 

 be obtained with so small an amount as 20 c.c. of blood. 



