292 THE TECHNOLOGY OP SOME OF 



beautiful coal-tar dyes (Technologist, vol. ii. p. 428). Having the 

 peculiar odour as well as flavour of oil of bitter almonds, nitro-benzole 

 forms an efficient substitute for that substance both as a flavouring and 

 perfume, and is often sold for such purposes under the name of essence 

 of mirbane. For culinary uses nitro-benzole has the great advantage of 

 being innocuous whilst the oil of bitter almonds is a deadly poison* Its 

 chief application as a perfume is in soap-making, and for this purpose 

 it is found to be better adapted than the true oil. 



Both Benzole and Naphtha are highly inflammable, burn with a dull, 

 smoky flame, but in a properly constructed lamp they yield on com- 

 bustion a cheap and brilliant light. Some years ago naphtha was ex- 

 tensively used, being burnt in a lamp of similar construction to the 

 paraffine lamps, or in a state of vapour as Holliday's lamp. But on 

 account of the extreme volatility of naphtha, and the property which 

 the vapour has of forming an explosive mixture with atmospheric air, 

 leading to serious accidents, the use of this substance is completely 

 superseded by the various paraffine oils, except in the instance of the 

 flamingandsmokylightused at our markets and fairs : mixed with alcohol, 

 naphtha constitutes an efficient burning fluid, and is largely used on the 

 Continent where spirit is cheap. Some such compound has, I believe, 

 lately been proposed to take the place of oil for lighting railway car- 

 riages, the liquid being burnt in a state of vapour by an appropriate 

 arrangement. 



Ordinary coal gas when transmitted through naphtha or benzole 

 receives a considerable addition to its illuminating powers. Mr. Lowe 

 upwards of twenty years ago first suggested and patented this method. 

 He passed coal gas through a rectangular box containing trays of 

 naphtha ; in passing over it the gas became impregnated with the hydro- 

 carbon. He calculated that 1,000 cubic feet of naphthalised gas 

 were equal in illuminating power to 2,000 cubic feet of ordinary gas, and 

 that the saving to the consumer by adopting his process was twenty-five 

 per cent. Within the last year or two this plan has been adapted to 

 many of the London street lamps, and has been made a subject of 

 special investigation by Dr. Letheby. He says, for this purpose the 

 naphtha must be colourless and of a sp. gr. not less than 0-830, and 

 not more than 0'860, and should yield 70 per cent, of volatile naphtha at 

 266°, and 20 per cent, at 302°. This gives continuously eight grains 

 of hydro-carbon to each cubic foot of gas, and raises the illumi- 

 nating power 60 per cent, over the unnaphthalised. A company 

 has lately been established in this country to carry on the naphtha- 

 lising of gas as well as to burn it in a state of vapour mixed 

 with air, under the name of the atmospheric light. The latter plan of 

 lighting was tried some years ago in America and abandoned, I believe, 

 on account of its impracticability. The plan is to drive a current of air by 



* That nitro-benzole in food is innocuous is questionable from several recent 

 oases that have come before the public. —Editor. 



