494 
DR. PLAYFAIR ON THE NITROPRUSSIDES, 
The combustions were made in the usual way. 
I. 8*350 grs. gave 0*252 gr. water and 4*045 grs. carbonic acid, 
II. 8*385 grs. gave 0*234 gr. water and 4*150 grs. carbonic acid. 
III. 7’900grs. gave 0*183 gr. water and 3*820 grs. carbonic acid. 
IV. 9*415 grs. gave 0*120 gr. water and 4*577 grs. carbonic acid. 
As this salt was well calculated to give correct knowledge with regard to the com- 
position of the nitroprussides generally, the nitrogen was carefully determined by the 
three best processes, viz. those of Dumas, Liebig and Bunsen. 
I. Quantitative estimation of nitrogen ; — 
6*808 grs. salt gave 69 C. C. nitrogen gas, 
the thermometer being 7°’7 C. and the barometer 30*094 inches. This makes the 
nitrogen 19*299 per cent. 
II. Liebig’s method : — 
Tubes. 
1. 
Vol. mixed gases. 
21*0 
Vol. after absorption. 
8*15 
Vol. of carbonic acid. 
12*85 
2. 
18*4 
* 7-3 
11*1 
3. 
24*0 
9*25 
14*75 
4. 
20*15 
7*45 
12*70 
5. 
13*3 
5*35 
7*95 
6. 
26*20 
9*2 
17-0 
123*05 
46*70 
76*35 
Hence the proportion of nitrogen to carbonic acid is as 1 : 1*63. This, calculated 
on 13*288, the mean quantity of carbon, gives 19*02 per cent. 
Bunsen’s method : — 
Obs. vol. Barom. 
inches. 
Vol. of mixed gases (moist) . 110*8 737’7 
Vol. after absorption (dry) . 46*2 761*9 
Corrected vol. of mixed gases . . 
Corrected vol. of nitrogen 
Vol, of carbonic acid 
Therm. 
16*2 C 
16*2 
66*801 
25*800 
41*001 
Col. mere. 
217*0 
218*0 
Hence the proportion of nitrogen to carbonic acid is as 1 : 1*589, which calculated 
on 13*288 carbon, gives 19*512 per cent. 
Iron . . . 
I. 
13*012 
11. 
12*934 
111. 
13*076 
IV. 
13*106 
Mean. 
13*032 
5 
140 
Calculated. 
13*011 
Silver . 
50*546 
50*000 
49*925 
50*040 
50*128 
5 
540 
50*185 
Carbon . . 
18*211 
13*508 
13*177 
13*257 
13*288 
24 
144 
13*382 
Hydrogen . 
0*330 
0*310 
0*250 
0*140 
0*257 
2 
2 
0*185 
Nitrogen . 
19*299 
19*020 
19-512-) 
23*457 
19*277 
15 
210 
19*516 
Oxygen 
3*602 
4*228 
4*060 j 
4*118 
5 
40 
3*721 
100*000 
100*000 
100*000 
100*000 
100*000 
1076 
100*000 
