THE SOURCE OP LIGHT, HEAT, COLOUR, ETC. 221 



nevertheless, a beautiful colour, and one that promises to outlive the 

 fickleness of fashions' fancy. Fuschine is the synonym of this dye. 



A blue colour known as bleu de Paris, discovered by a French chemist, 

 and a green, aniline green or emeraldine, have also been produced from 

 aniline ; but I cannot learn that any success has yet attended their manu- 

 facture, or that they have really passed from the theoretical into the practi- 

 cal world. 



A beautiful orange colour very recently (and previous to that sad 

 bereavement which has filled the nations heart with sorrow) was enlivening 

 the shops of our metropolis under the designation of capucine, the French 

 name of the common garden nasturtium, 2 ropceolum majus, as bearing some 

 resemblance to its flower. This dye, I have every reason to believe, is pre- 

 pared from another coal-tar base, carbolic acid, as this substance when 

 treated with an excess of nitric acid yields picric acid, which is of itself 

 a beautiful orange yellow colour, and, as I suppose, the very dye in question 

 •" Capucine." The gum resin of the Australian grass trees, Xanthorrhcea sp.> 

 has been the chief source of picric acid hitherto, but carbolic acid must, 

 I should suppose, furnish a cheaper supply of raw material. It is obtained 

 from that portion of coal oils distilling over at a temperature of from 300° 

 to- 400°. Carbolic acid has likewise another application, to which I shall 

 allude presently. 



Naphthaline is a further basic substance from coal-tar which promises 

 us eventually a supply of useful colours. Popularly known in the gas 

 trade as the gas-makers' nuisance, from its corroding the pipes in large 

 quantities, and injuriously affecting the quality of the gas ; it possesses, in 

 the crude state, a most intolerable odour, and has the appearance of a mass 

 of mud ; but when sublimed, it occurs in beautifully white crystalline flakes 

 or scales, and the disagreeable odour, although not removed, is sensibly 

 diminished. Efforts have been made, as yet unsuccessfully, to elaborate 

 a blue from this base. There are also other hydro-carbon bases which 

 yield colour, and may yet be employed. 



The coal-tar colours, from their great brilliancy, are plainly discernible, 

 and readily distinguished from all other dyes, and yet withal they are not 

 coarse, but soft in effect, and if our chemists can but elaborate other shades, 

 and more decided colours, the ordinary dye-stuffs of commerce will at last 

 become curiosities and relics of the past. 



A few pigments are also obtained from the fossil hydro-carbons 

 Cologne earth is a species of brown coal. From certain kinds of peat 

 a brown pigment is prepared, termed peat umber, or humic acid ; and from 

 coal-tar a very good lamp black is produced. 



Miscellaneous Products. 

 The miscellaneous applications of the fossil hydro-carbons are both 

 numerous and important, every day, almost, adding to the long and inter- 

 esting category. Hundreds — yea, possibly thousands — of busy brains are 

 bestowing patient thought upon these fossil productions of Nature, which, 



