r:sT[MATIOX OF FAT — ADAMS' METHOD. 109 



and running the milk on to it from a pipette, afterwards noting 

 the weight of milk delivered by the pipette. He preferred to 

 use filter paper instead of the blotting-paper recommended hy 

 Adams. 



Vieth, immediately after the publication of the method, sub- 

 jected it to an exhaustive test, and criticised it somewhat severely. 

 He showed that blotting-paper contained matter soluble in ether, 

 and that, as Adams had ignored this, the fat estimations made 

 by Adams were too high ; he also showed that the substance in 

 filter paper soluble in ether was extracted with comparative 

 slowness by this solvent. Faber later showed the same thing. 



Notwithstanding these criticisms, the Milk Committee ap- 

 pointed by the Society of Public Analysts recommended its 

 adoption by their members ; it was indeed recommended that 

 the papers should be previously extracted, but nothing was said 

 of the difficulty of completely removing the matter soluble in 

 ether, it being implied that twelve siphonings were suflicient to 

 effect this. The recommendation of the Milk Committee was 

 adopted at a General Meeting of the Society, and it thus became 

 a quasi-official method. The use of this method for determining 

 total solids was abandoned. 



Notwithstanding the recommendation of the J\lilk Committee 

 that the coils should be extracted previously to use, it became 

 the general practice to omit this, and to use unextracted coils, 

 making a deduction, from the weight of total extract, of the 

 weight of the extract obtained from a coil when extracted alone 

 for the same length of time. 



The author showed that this last modification was not free 

 from error ; the matter soluble in ether was found to consist 

 chiefly of a calcium salt of resinous acids, which was only of 

 limited solubility in ether ; the acids themselves were much 

 more soluble, and when these were liberated by acids — even the 

 small amount of acid found in milk — a greater extract was 

 obtained in a given time. As the time usually allowed for 

 extraction (IJ hours) was not suflicient to remove the whole of 

 the soluble matter from the blotting-paper — as much as ten 

 hours being necessary — it followed that the matter extracted by 

 ether from the coil was greater when a milk (containing small 

 amounts of acid) was placed on a coil than when the coil was 

 extracted alone. The difference was represented by the amount 

 of resinous acids equivalent to the acidity of the mUlc, and was 

 naturally not constant. 



He found that alcohol completely extracted the coils — a fact 

 also noted almost simultaneously by Soxhlet — but preferred the 

 use of alcohol containing 10 per cent, of acetic acid. Ether 

 containing acetic acid was also efficacious. 



