Thialdine and Selenaldine. 473 



the facility with AAhich they crystallize and for the beauty of 

 the crystals. 



Thialdine and its salts are deconiposed when gently heated 

 with a solution of nitrate of silver ; sulphide of silver is pro- 

 duced with disengagement of a combustible gas, easily in- 

 flammable and possessing the odour and all the properties of 

 aldehyde ; namely, it is entirely absorbed by concentrated 

 sulphuric acid and solution of potassa, the former becoming 

 brown immediately, the latter remaining clear but depositing 

 when gently heated a yellowish-brown precipitate of resin of 

 aldehyde, and assuming the peculiar and offensive odour 

 which accompanies the decomposition of aldehyde under these 

 circumstances. 



When thialdine is ignited with lime, chinoline appears 

 among the products of decomposition, which may be easily 

 recognised by its characteristic odour and by its beautiful 

 platinum salt. 



With cyanide of mercury thialdine exhibits a peculiar com- 

 portment. On. mixing the two solutions a white precipitate 

 is produced, which on boiling is converted into amoi'phous, 

 black sulphide of mercury. If this decomposition takes place 

 in a retort its neck becomes coated with fine crystalline nee- 

 dles, extremely volatile, insoluble in water but easily soluble 

 in alcohol and aether. This new body, in which part or all the 

 sulphur appears to be replaced by cyanogen, is formed in but 

 small quantities, which up to this moment has prevented us 

 from studying it any further. 



The analysis of thialdine was performed in the usual way ; 

 the combustion with oxide of copper is attended with diffi- 

 culties, as the conversion of carbon into carbonic acid is ob- 

 structed by the large quantity of sulphur contained in the 

 body forming a corresponding amount of sulphide of copper 

 at the point of contact between the substance and oxide of 

 copper. 



On burning thialdine with oxide of copper and sepai-ating 

 the sulphurous acid formed by means of peroxide of lead, a 

 gas is obtained containing volumes of nitrogen and carbonic 

 acid in the proportion of 1 : 12. Aldehydite of ammonia, 

 from which thialdine is produced, contains 4 cquivs. of car- 

 bon to 1 equiv. of nitrogen, from which it is evident that al- 

 dehydite of ammonia on being converted into thialdine by 

 means of hydrosulphuric acid has lost two-thirds of its nitrogen. 



We have mentioned that thialdine, on being gently haated 

 with a solution of nitrate of silver, has its sulphur converted into 

 sulphide of silver. This mode of decomposition was employed 

 to determine the sulphur. TIic nitrogen of the thialdine re- 

 mains in the residuary liquid in the form of ammonia^ from 



