SYNTHETIC ORGANIC PRODUCTS 481 



The same sort of guncotton dissolves in a mixture of alcohol and 

 ether, giving a solution called collodion, used in photography and 

 in medicine. 



When collodion is forced under great pressure through minute 

 holes in a steel die, the threads dry as they issue from the open- 

 ings and can be wound on spools. The product is treated with 

 an alkali, which decomposes the ester, leaving a material of the 

 composition of the original cotton. The product is another 

 form of artificial silk (p. 399). 



Another plastic, not chemically related to the preceding, is 

 bakelite, prepared from formaldehyde CH 2 and phenol C 6 H 5 OH 

 (carbolic acid) . Under suitable heat treatment the mixture grad- 

 ually sets to a solid, hard, infusible, resinous mass, which is insol- 

 uble in ail common solvents. Before it sets, it can be dyed or 

 " filled," and it can be applied as lacquer, or moulded to any form. 

 Switchboards, dolls, ornamental buttons, artificial jewels, phono- 

 graph records, billiard balls, and stereotyping matrices are 

 amongst the objects into which it is now fashioned. 



Explosives. Nitroglycerine. Some inorganic explosives, 

 gunpowder (p. 372) and ammonium nitrate (p. 302), have been 

 discussed in earlier chapters. The main organic explosives are 

 also compounds of nitrogen. 



As already mentioned, the alcohols interact with inorganic 

 acids, as well as with organic ones, to produce esters. A familiar 

 illustration is met with in the manufacture of nitroglycerine 

 (glyceryl trinitrate) by the action of glycerine and nitric acid: 



C 3 H 5 (OH) 3 + 3HN0 3 - C3H 5 (N0 3 )3 + 3H 2 0. 



To assist in the liberation of the water, the nitric acid is mixed 

 with a dehydrating agent. The glycerine then is added slowly 

 to the cooled reagents. The nitroglycerine is an almost color- 

 less oil which floats to the surface of the acid mixture. It is 

 shaken repeatedly with water, in which it is insoluble, and then 



