220 ANNUAL OF SCIENTIFIC DISCOVERY. 



substance, is added, together with an equal quantity of a saturated solu- 

 tion of carbonate of ammonia. The mixture should again be thoroughly 

 stirred, and then turned into suitable vessels and hermetically sealed. To 

 the carbonate of ammonia it may be well to add one-eighth its weight of the 

 liquid or caustic ammonia of the Pharmacopeias. 



NEW METHOD OF VULCANIZING INDIA-RUBBER. 



"When flowers of sulphur and dry hypochlorite of lime (bleaching powder) 

 are shaken together, a very strong odor of chloride of sulphur is immediately 

 developed. If the mixture be somewhat forcibly rubbed in a mortar, eleva- 

 tion of temperature ensues, the sulphur softens, and the mixture becomes 

 solid, while abundant vapors are evolved. When a much larger amount of 

 sulphur than that of the hypochlorite is used, and friction is avoided when 

 the two are blended, a mixture is obtained, which, being added to the 

 caoutchouc paste either with or without the addition of inert matters, such 

 as chalk, oxide of zinc, etc., serving to give body to the product effects 

 the vulcanization of the latter, either at the ordinary temperature or when 

 gently heated. By this means objects of any thickness can be uniformly 

 vulcanized. 



If, instead of employing an excess of sulphur, an excess of the hypochlorite 

 be introduced into the mixture, and this be agitated, so much heat will be 

 developed that the vessel containing the mixture can no longer be held in 

 the hands ; if the flask be closed, the action becomes so violent that the cork 

 will be blown out, or the flask broken by a violent explosion. M. De 

 Clauberg, Comptes Rendus. 



IMPERISHABLE INK. 



Mr. John Spiller has communicated to the London Chemical Neics a paper 

 on the employment of carbon as a means of permanent record. The imper- 

 ishable nature of carbon, in its various forms of lamp-black, ivory-black, 

 wood-charcoal, and graphite, or black lead, holds out much greater promise 

 of being usefully employed in the manufacture of a permanent writing 

 material ; since, for this substance, in its elementary condition, and at ordi- 

 nary temperatures, there exists no solvent nor chemical reagent capable of 

 effecting its alteration. 



The suggestion relative to the mode of applying carbon to these purposes, 

 which it is intended more particularly now to enunciate, depends on the fact 

 of the separation of carbon from organic compounds, rich in that clement, 

 sugar, gum, etc., by the combined operation of heat and of chemical reagents, 

 such as sulphuric and phosphoric acids, which exert a decomposing action in 

 the same direction; and by such means to effect the deposition of the carbon 

 within the pores of the paper by a process of development to be performed 

 after the fluid writing ink has been to a certain extent absorbed into its sub- 

 stance, a system of formation, by which a considerable amount of resistance, 

 both to chemical and external influences, appears to be secured. An ink of 

 the following composition has been made the subject of experiment : 



Concentrated sulphuric acid, deeply colored with indigo, 1 fluid ounce. 



\V"fpv fi " " 



v uitri j . . . . . , . . . . o 



J.i a i 'puaar, ... 1 ounce troy. 



Strong mucilage of gum-arabic, . . . 2 to 3 fluid ounces. 



