[ 492 ] 

 LXXII. Proceedings of Learned Societies, 



ROYAL SOCIETY. 



[Continued from p. 369.] 



April 11. — A paper was read, entitled, " On a new equi-atomic 

 compound of Bicyanide with Binoxide of Mercury." By James F. 

 W. Johnston, Esq., F.R.S. 



In this paper an account is given of the properties of a salt, ob- 

 tained by agitating with red oxide of mercury a small proportion of 

 hydrocyanic acid, and which the author finds to be distinguished 

 from the bicyanide of mercury by its sparing solubility in cold water, 

 by the strong alkaline reaction exhibited by its solution, (a property 

 which indicates an excess of mercury,) and by its susceptibility of 

 detonation by heat, depending on this excess being in the state of 

 an oxide, and on the action of the oxygen on a portion of the car- 

 bon of the cyanogen it contains, and the presence of which is shown 

 by the disengagement of hydrocyanic acid gas when acted on by 

 hydrosuljihuric and hydrochloric acids. 



Tlie analysis of this salt, given by the author, shows it to con- 

 sist of 



Carbon 5-203 



Nitrogen 6-025 



Oxygen 3-098 



Mercury 85-674 



100. 



'J'he formula of which composition is as follows : 

 Hg. Cy.,. + Hg. O.,. 



April IS. — The following papers were read, viz. — 

 " On the Constitution of the Resins." Part I. By James F. W. 

 Johnston, Esq., F.R.S. * 



The object of the general investigation, of which the commence- 

 ment is given in this paper, is to determine the relative composition 

 of the various resins which occur in nature, and to trace the analogies 

 they exhibit in their constitution ; and also to ascertain how far they 

 may be regarded as being derived from one common principle, and 

 whether they admit of being all represented by one or more general 

 formulae. 



The chemical investigation of the resin of mastic shows that this 

 substance consists of two resins ; the one soluble, and acid ; the 

 other insoluble, and having no acid properties. The formulae ex- 

 pressing the analysis of each of these are given by the author. He 

 also shows t>.at a series of analyses may be obtained which do not 

 indicate the true constitution of a resin. The soluble resin, when 

 exposed to the prolonged action of a heat exceeding 300° Fahr. is 

 partly converted into a resin containing three, and partly into one 

 containing five equivalent parts of oxygen, the proportion of carbon 

 remaining constant. The same resin combines with bases, so as to 



* See our present volume, p. 340. 



