21 4 Dr. Playfair on the Nitroprtissides, 



light ; its solutions on long keeping deposit prussian blue and 

 become partially decomposed. 



The crystals of this salt are of a dark red colour. 

 The analysis was made by decomposing the salt by Nord- 

 hausen sulphuric acid. The following estimations give the 

 amount of water lost in the water-bath : — 



I. 14-865 grs, lost 1-765 gr., or 11-873 per cent. 

 II. 15-455 grs. lost 1*855 gr., or 12-002 per cent. 



III. 12-430 grs. lost 1*480 gr., or 11*906 per cent. 



IV. 20-155 grs. lost 2-245 grs., or 11*138 per cent. 



Mean . . 11*730 

 The inorganic analyses yielded the following results : — 

 I. 23*905 grs. gave 6*479 grs. peroxide of iron and 13-837 

 grs. sulphate of potash. 

 II. 20-145 grs. gave 5-525 Fe^O^ and 12-105 KO, SO^. 



III. 13-015 grs. gave 3-550 Fe^O^ and 7-66 KO, SO^. 



IV. 12-945 grs. gave 3*536 Fe^O^ and 7-60 KO, SO^. 

 V. 17*195 grs. gave 4-832 grs. peroxide of iron. 



The organic analyses were made with chromate of lead, 



I. 7*475 grs. gave 0*448 gr. water and 5*403 grs. carbonic 

 acid. 

 II. 7*122 grs. gave 0*425 HO and 5*105 C0«. 



I. II. III. IV. V. Mean. 



Iron . . 18*972 19*198 19*093 19*120 18*901 19056 



Potassium 25-947 26-934 26*385 26*388 ... 26*413 



Carbon . 19*712 19*548 19*630 



Hydrogen 0*665 0*663 0*664 



o^^^Th^j^ j^ 



100-000 100-000 100-000 



These results may be expressed by the following calcula- 



tion 



5 Iron . . 



5 Potassium 

 24 Carbon . 



3 Hydrogen 



15 Nitrogen 



6 Oxygen . 



Calculated. Mean. 



140 18*92 19*056 



195 26*35 26*413 



144 19*46 19*630 



3 0*40 0*664 



210 28*381 . 



48 6*49 J "^^ ^•'*' 



740 100*00 100*000 



According to this calculation the formula of the salt dried 

 at 212° is F^Cyi23NO, 5K + 3HO; the salt loses in the water- 

 bath 11*73 per cent, of water; had it lost 12*7 per cent, this 



