THE TECHNOLOGIST. [Atjotst 1, 1864. 



24 ON CHEMISTRY APPLIED TO THE ARTS. 



acid, and as the substitution is made by Messrs. Letchford without any 

 increase of cost, the price of these matches is as low as that of the com- 

 mon ones. These gentlemen have also found the means of diminishing 

 the amount of phosphorus used to a very considerable extent, so that 

 the disagreeable smell of this substance is also avoided. But the greatest 

 improvement that Messrs. Letchford have made is in what they call 

 their hygienic matches, or lights, in which for the first time amorphous 

 phosphorus is substituted for ordinary phosphorus, and in small quanti- 

 ties. The advantage of these matches cannot be overrated, for children 

 can eat them with impunity, as amorphous phosphorus is not poisonous ; 

 they are not nearly so combustible, and therefore not so likely to cause 

 accidental fires ; and lastly, all source of injury to the health of those 

 employed in the manufacture is removed. I cannot leave this subject 

 without still drawing your attention to one or two important facts. 

 Messrs. Hochstetter and Canouil, besides others, have lately introduced 

 chemical matches free from phosphorus, which are stated to have the 

 following composition : 



Chlorate of Potash 10 10 10 



Hyposulphite of Lead ... 26 26 20 



Peroxide of Lead 9 - 8 



Peroxide of Manganese ... 336 



Chromate of Lead 17 4 8-8 



Gum Arabic 4 4 4 



An important improvement in the manufacture of chemical matches is 

 the reduction of the proportion of phosphorus to a minimum. This is 

 effected by reducing the phosphorus to an infinitesimally minute divi- 

 sion, by which the manufacture is rendered more economical, and the 

 matches, when ignited, have less of the unpleasant odour of phosphorus. 

 This division is accomplished by using a solution of phosphorus in bi- 

 sulphuret of carbon, by which a saving of 19-20ths of the phosphorus is 

 obtained. Another invention is that of Messrs. Puscher and Reinsch, 

 who have proposed the employment of sulphide of phosphorus. 



Ivory. — The lecturer having given some details respecting the pro- 

 perties of ivory, said : I will now call your attention to the substitution 

 of the following mixture for ivory tablets as applied in photography. 

 Finely-pulverised sulphate of baryta is mixed with gelatine or albumen, 

 compressed into sheets, dried, and polished ; these sheets are ready for 

 use in the same way as ivory plates. You are all doubtless aware that 

 the nut of the Phytelephas macrocarpa, of the palm-tree tribe, has for 

 many years been used in this country as a substitute for ivory for 

 small articles, and it may be interesting to you to be made acquainted 

 with the two following facts, viz., that the nut is composed of — 



Pure cellulose 81 per cent. 



Gum 6 „ 



Kitrogenated principles ... 4 „ 



Water 9 „ 



Total 100 



