274- Dr. PJayfair on the Nitroprussides, 



Obs. vol. liarom. Therm. Col. Merc, 



inches. o 



Vol. of mixed gases (moist) 89*5 29*994 7*0 C. 152'7 



Vol. after absorption (dry) 37*4 30-015 9-2 C. 205-2 



Corrected vol. of mixed gases . . . 52*995 

 After absorption of carbonic acid . . 20'570 



Nitrogen . . . 32-425 



Hence the proportion of nitrogen to carbonic acid is 

 1: 1-576. 



I. II. III. Calculated. 



Iron. . . 23-88 23-69 23-85 5 140 24-26 



Carbon . . 24-74 24-92 24-75 24 144 24-95 



Hydrogen . 1-69 1-71 1-77 H H 1*90 



Nitrogen . 36*73 36*73 36*73 15 210 36-39 



Oxygen . 12*96 12*95 12-90 9 72 12*50 



100-00 100-00 100*00 577 100*00 



The calculated result, especially as regards the hydrogen, 

 is not sufficiently close to be the true expression of the ana- 

 lysis, but it is here given to show how far the acid differs from 

 pure nitroprussic acid. It is indeed probable that the acid 

 dried at 212° only contains 10 equivs. of water. 



The acid is so remarkably deliquescent that it is very diffi- 

 cult to ascertain how much the crystals lose in the water-bath. 

 The following analysis of the salt dried in vacuo over sulphuric 

 acid shows a higher state of hydration. The sample analysed 

 had never been heated, even in solution, so that it evaporated 

 without the deposition of oxide of iron. Still the oxide was 

 detected in the mother-liquor by ferrocyanide of potassium. 

 I. 3*225 grs. gave 1*010 gr. peroxide of iron. 

 II. 3*235 grs. gave 1*020 gr. peroxide of iron. 

 I. 5*830 ^rs, gave 5*020 grs. carbonic acid and 1*09 gr. 

 water. 



II. 8*225 grs. gave 7'060 grs. carbonic acid and 1*51 gr. 

 water. 



I. 

 Iron . . . 21*92 

 Carbon . . 23*48 

 Hydrogen . 2*07 

 Nitrogen 

 Oxygen 



10000 100*00 100*00 



A silver salt made from the well-crystallized acid showed 

 that the iron was in excess, and that the carbon was in the 

 usual proportion (see pp. 280, 281). The analyses of these 

 silver salts are given further on, in order to avoid repetition. 



•T 52*53 



