54 Ojjice of the Nitrogen of the Air, 



2. As to the nature of cyanogen, which it is important to under- 

 stand in this enquiry, it may be stated that Gay-Lussac has ascertain- 

 ed by detonating that gas with a due proportion of oxygen that one 

 hundred measures of cyanogen require two hundred of oxygen for 

 complete combustion, that no water is formed, and that the products 

 are two hundred measures of carbonic acid and one hundred of ni- 

 trogen. From which it follows that cyanogen contains its own bulk 

 of nitrogen and twice its volume of the vapor of carbon, and conse- 

 quently consists of 1 proportional of Nitrogen, and 2 proportionals of 

 Carbon. 



3. Cyanogen is obtained from blood as well as other animal mat- 

 ters by various processes, though the opinion heretofore maintained 

 by chemists is, that it is generated during the processes employed, and 

 that it does not exist ready-formed in the blood. But upon studying 

 the processes with attention, it will be found that they all have in view 

 the formation of the hydro, or ferrocyanates ; and no attempt has to my 

 knowledge been made to obtain the cyanogen in a separate state. 

 Granting, however, that cyanide of iron or even of mercury existed 

 in the blood, would the process for obtaining Prussian blue differ from 

 that now adopted ? I answer no. The same steps would be necessa- 

 ry ; — the decomposition of the cyanide by means of an alkaline metal 

 would require the application of heat, and after that, the addition of 

 the sulphate of iron would furnish the ferrocyanate. 



4. The view which I have proposed will happily reconcile the 

 discordant results of chemists concerning the existence of iron in the 

 blood. This point has exercised the ingenuity of some of our ablest 

 chemists. Although iron had been detected in the ashes of blood 

 by several, it is only lately that we have been made acquainted with 

 a method of proving its existence by the liquid tests. This meth- 

 od was discovered in 1825, by Dr. Engelshart a German Chemist. 

 It consists in transmitting a current of chlorine gas through a solution 

 of the red globules, upon which the color disappears, white flocks 

 are thrown down, and a transparent colorless solution remains in which 

 the peroxide of iron can be detected by the usual reagents. These 

 results have since been confirmed by Professor Rose and other chem- 

 ists. 



Now it is believed that the presence of cyanide of iron cannot be 

 detected by any of the liquid tests with which we are acquainted, or 

 in other words, that the iron in this compound cannot be made ap- 

 parent. But it has been ascertained by M. SeruUas that when mois- 



