246 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [16] 
solution gives an appreciable vapor tension, as has been shown by 
Wiillner (Pogg. Annalen 110, S. 570). Wiillner’s statements are not 
perfectly clear at first reading, but the facts appear from his formula for 
the tension, V = .0032T — .00000432T’, where V is the decrease of ten- 
sion for every part of “pentahydrate of potash” to 100 of water (0.51 
K,O to 100 H, O.) and T the vapor tension of pure water. Several de- 
terminations of the vapor tensions of the solutions actually used were 
made by my friend and assistant, Dr. J. H. Long, who has devoted con- 
siderable attention to these subjects, and who conducted the investiga- 
tion here referred to. The results were in harmony with Wiillner’s 
formula. 
Applying both corrections for residual air, Dr. Long obtained, in 
determinations of nitrogen in several samples of fish, results agreeing 
very closely with those obtained with the soda-lime method by Messrs. 
Woods and Beamer, as appear from the following figures: 
Soda-lime method. 
Absoluto 
method. 
a. b. Average. 
PRO MP SM CON: INiccscsbeccsccccecess = : 5. 82 5. 88 5. 85 5. 95 
XLII. Per cent. N. : 10. 77 10. 75 10. 76 10. 76 
XLV. Per cent. N . 13. 85 13. 79 13. 82 13. 91 
XLVI. Per cent. N . 10.19 10. 24 10. 22 10. 22 
XLVI. Percent. N . 11. 91 11. 89 il. 90 11. 95 
L. Percent.N .. ahh e245) 11. 85 11. 85 11. 78 
TPR SriCentaiNi seawsccss «cehece<nte es 10. 85 10. 83 10. 84 10. 83 
PP SrcentaN j= sscs. co cachove ect cs choc eeetecee eee 14. 84 14. 86 14. 85 14. 87 
It may be added that previous comparative trials with ammonium 
sulphate and oxalate had given closely concordant results. Thus, Dr. 
Long found by the absolute, and Mr. Woods by the soda-lime method, 
the following percentages of nitrogen *: 
Absolute method. Soda-lime method. 
| | 
Aver- Aver- 
a. b. c. d. age. a. b. ago. 
Ammonium. sulphate,............ 0s... 21:24 || 21.16) | 20229) | St Bou) 2122852 eS Dts 21.18 
PAMITTYO MUI OX. ACG | \-\5.0:0:= -\-\eisiesin.clceicicuic | 19.84] 19.75 | 19.71 ]|......-- LO NTT LEMOS) oa nt 19. 68 
| | 
Ash.—The ash was determined in the flesh in the same way as in the 
hot and cold water extracts, namely, by charring, extracting with water, 
burning the residue, adding the solution to the residue, evaporating and 
burning. The crude ash thus obtained was practically free from coal, 
and had, naturally, no sand. No determinations of carbonic acid in the 
ash were made. About 5 grams of substance were used for each deter- 
*It may be worth while to add that direct determinations of ammonia by distilla- 
tion with caustic alkali gave in the ammonium sulphate, 21.19, 21.21, and 21.22%, 
average 21.219; with ammonium oxalate, 19,78 and 19,749, average 19.769, results 
midway between those by the two methods above, 
