58 Messrs. Glassford and Napier on the 



pupil of his, Mr. F. Rodgers, and his brother; on referring 

 to their Memoir, published in the Philosophical Magazine 

 of February 1834, we find a different statement from what 

 Dr. Turner makes; they say, " L. Gmelin prepared a double 

 cyanuret of cobalt and potassium, analogous to the red cya- 

 nuret of iron and potassium." These different statements of 

 apparently the same thing must have arisen either from the 

 want of proper care in naming the salts, so as to indicate to 

 which class they belong, or to the want of sufficient evidence 

 respecting their constitution. We may render this still more 

 evident by the following statements. Berzelius mentions a 

 cyanure platinoso-potassique,or platino-cyanuret of potassium, 

 but on referring to its alleged constitution, we do not find, as 

 its name indicates, a compound of platina similar to theferro- 

 cyanuret of potassium, but a compound totally different from 

 either the yellow or red prussiate of potassa ; the same salt is 

 described in Graham's ' Elements,' p. 991 ; and there also it is 

 called the platino-cyanide of potassium. The acid described 

 in some chemical works as the platino-cyanic acid, does not 

 resemble in constitution the ferro-cyanic acid, as its name in- 

 dicates. If, therefore, there be a necessity for distinguishing 

 the acid formed by the supposed salt radical ferri-cyanogen 

 with 3 eqs. of hydrogen, from that formed by ferro-cyanogen 

 with 2 eqs. of hydrogen, so then there is an equal necessity 

 for distinguishing a metallo-cyanogen, which combines with 

 2 eqs. of hydrogen, from a metallo-cyanogen, which combines 

 with 1 eq. of hydrogen : for the same reason also platino- and 

 other cyanides of potassium should receive appellations which 

 indicate their constitution, and not such as by analogy lead 

 us to infer a totally different constitution. These remarks 

 tend to show us the necessity of cai'efully re-examining the no- 

 menclature of this apparently complex subject, and the scru- 

 pulous care with which we ought to classify and name these 

 compounds, so as neither to misrepresent their constitution, 

 nor to leave the possibility of their being ascribed to classes 

 to which they do not belong. 



4. We deem these observations necessary for the purpose 

 of alluding to a memoir by Mons. A. Meillet, which appeared 

 in the Journal de Pharmacie et de Chemie for June last, and 

 which was translated into the Philosophical Magazine for 

 August, entitled, " On some new combinations of Cyanogen." 

 The author says, " The peculiar manner in which cyanogen 

 acts towards iron, by forming two very stable acids with it, 

 leads to the supposition that it is not the only metal with 

 which cyanogen is capable of combining. In fact, some Ger- 

 man chemists, and Gmelin among others, have discovered 

 three new compounds, which are platino-cyanogen, cobalto- 



