Intelligence and Miscellcmeoits Articles. 1 45 



with the assistance of heat; equal quantities, sublimed with a strong 

 heat, yielded a substance which was crystalline on the inner surface, 

 and of a yellowish white colour ; it was partly soluble in water, and 

 contained some insoluble protobromide. It may also be prepared 

 by heating equal quantities of bromine and mercury under water. 

 The mixture becomes pasty, and by evaporating the fluid, silky 

 needles of perbromide are formed. Or the evaporation may be con- 

 tinued to dryness, and the residue sublimed ; when purified by sub- 

 limation, it has the form of very fine silky needles, which are very 

 soluble, have a penetrating smell and are very volatile. It is pre- 

 cipitated yellow by potash, and red by chromate of potash. 

 It is composed of Mercury .... 59*47 

 Bromine .... 46*53 



100 



All the bromides above described readily give out bromine by the 



action of chlorine. . 



ATOMIC CONSTITUTION OF CYANIDE OF MERCURY. 



Mr. J. F. W. Johnston, M.A., who supposed he had disco- 

 vered that clorine is evolved, when carbonate of manganese is treated 

 with diluted sulphuric acid, has published a memoir in Dr. Brewster's 

 Journal for the last month, the object of which is to " determine by 

 experiment the atomic constitution" of cyanide of mercury. 



Mr. Johnston admits that the constituents of the compound in 

 question have been " correctly made out ;" and if this be the case, 

 we would inquire whether experiment can go further ? To us it 

 appears, that when the analysis of a compound has been performed, 

 theory is to determine its atomic constitution. Thus, Dr. Henry 

 and Dr. Thomson agree, that the red oxide of copper consists of 64 

 copper, 8 oxygen ; but while the former chemist considers it to be 

 a compound of one atom of each of its elements, the latter regards 

 it as constituted of two atoms of copper and one atom of oxygen. 



An examination of various authors would also have saved Mr. 

 Johnston the trouble of an analysis; for he might have seen, that 

 the conclusion at which he has arrived, that the compound in 

 question is a bi-cyanide, but which he supposes is " nowhere to 

 be found," is to be met with in the following authors : Mr. Brande, 

 Manual of Chemistry, 1819, p. 306; Mr. Brande, Tables of Definite 

 Proportionals, 1828, p. 63 ; Dr. Paris, Medical Chemistry, 1825, 

 Appendix; Dr. Henry, Elements of Chemistry, J 826, vol. ii. 

 p. 664; Dr. Turner, Elements of Chemistry, 1828, p. 519. K. P. 



CARBAZOTATES OE COPPER AND LI AD. 



M. Liebig finds that carbazotate of copper crystallizes in long 

 rhombic needles, of an emerald green colour. They arc readily 

 soluble in water, and losing water by exposure to tlie air they be- 

 come yellow. 



Carbazotate of lead explodes when struck between two pieces of 

 iron. It may be used with the same advantages, and with less dan- 

 ger than fulminating mercury, for percussion guns. 



A concentrated solution of carbazotic acid is precipitated by di- 

 N. S. Vol. 6. No. 32. Aug. 1829. U luted 



