72 IOWA ACADEMY OF SCIENCES. 



These results compare favorably with those from glass just reported. 



Next, to imitate the condition of Stutzer's process, copper hydrate, as well 

 as a mercuric salt and K., S, was added. Results after deducting the blank 

 were as follows : 



IN COPPER 

 FLASKS. 



No. of C.C. of decinormal acid neutralized 14.2 



14.2 



14.3 



14.25 



14.25 



Mean of five 14.24 



Here again, the results were practically identical with those obtained by 

 distilling from glass. 



The plan was then tried upon the product of the Kjeldahl digestion in 

 fodder analysis, both in total and albuminoid nitrogen determination, the 

 results in all cases bemg in substantial agreement with those obtained by 

 distilling from glass; and now we use the metallic flasks in the regular an- 

 alytical work of the laboratory. A few results will suflice to illustrate: 



SUBSTANCE TAKEN. RESUIiTS— IN COPPER. IN GLASS. 



Sborts, total Nitrogen 2.81 per cent. 2.81 per cent. 



Shorts, Albuminoid Nitrogen 2.26 '■ 2.26 



Cream Gluten Meal, total Nitrogen 6.28 " 6.27 " 



Cream Gluten Meal, Albuminoid Nitrogen -j ^'.^^ [[ ^'H 



Sugar Meal, total Nitrogen 3.3a " 3.19 " 



(Determinations made two months apart.) 



We employ 200 c.c. of water in transferring the contents of the digestion 

 flask into the distilling flask, using about half of it in diluting and cooling 

 the acid licquid before actually transferring. We are also in the habit of 

 introducing 80 c.c. of the K-iS solution, instead of 35 c.c. as is usually 

 directed. This may not be necessary, but the fact that the residual liquid 

 after distillation is always free from (binary) sulphur, the excess being re- 

 moved by the flask itself, seems to render a little extra sulphide advisal^le. 

 This action between the sulphide and the copper will doubtless in time de- 

 stroy the flasks; but long before that time arrives, the.y will have saved in 

 glassware manj^ times their cost. 



The flasks are heated by rather small, naked flames; a large flame under 

 the one pint flask will boil the charge over. The receiving flasks ai'e marked 

 at the 200 c.c. level to show when the operation is flnished. No zinc or pumice 

 is required to prevent "bumping ;" otherwise, the arrangements are as usual. 



The distillation is completed within thirty minutes; so the saving of time 

 is very gi-eat. 



Iowa Agricultural Experiment Station, Ames, Iowa. 



