CHEMICAL SCIENCE. 227 



The greater part of the dead oil, too, has no further process to undergo. 

 The product is in reality a rough mineral creosote, and possesses in a high 

 degree the antiseptic properties for which creosote is so celebrated. The 

 dead oil is about the most important thing got out of the tar; thousands 

 and thousands of gallons are every week sold to the different railway com- 

 panies for the soaking of sleepers and other timber; for, once well impreg- 

 nated with the fluid, every description of wood may bid defiance to both wet 

 and dry rot. A good deal of the oil is, however, used for a very different 

 purpose. It is exceedingly inflammable, and contains a large amount of 

 carbon ; and these two peculiarities are taken advantage of by slowly burning 

 it in curious little lamp-furnaces connected with vast brick flues; the smoke 

 from the burning oil is rapidly deposited on the sides of these flues in a form 

 which washerwomen would recognize as " blacks; " and being periodically 

 scraped off, it makes its appearance in the market as "lampblack." 



The light oil is, however, a substance requiring a good deal more prepara- 

 tion, and serving a greater variety of purposes, than any of the other pro- 

 ducts. Light oil is impure coal naphtha; and to free it from its impurities, 

 especially those affecting its color and smell, is the crowning object of the 

 tar-distiller. 



As it comes over, in the first instance, it is a dark-brown liquid, smelling 

 most horribly. Being, in this state, all but useless, it is at once redistilled, 

 and loses a large amount of smell and color. It is now ordinary "naphtha," 

 and used for a variety of purposes, but it still contains a large quantity of a 

 peculiar greasy matter, called " paranaphthaline," from which no amount of 

 distilling would entirely free it. To separate it from this paranaphthaline, 

 therefore, it is mixed with " oil of vitriol," in an iron reservoir, and the acid 

 and naphtha are thoroughly shaken and stirred together. For some little un- 

 derstood reason, the fatty paranaphthaline leaves the naphtha, and attaches 

 itself to the acid, carrying along with it a vast amount of impurity, and 

 leaving the naphtha in a very commendable state of cleanliness. As the oil 

 of vitriol is nearly three times as heavy as the naphtha, directly the stirring 

 and mixing process is at an end, the two bodies separate, and are drawn off 

 from the reservoir into proper receptacles. 



The naphtha is now either sold in its present condition, or again distilled. 

 For the most particular purposes, indeed, it is distilled or rectified three 

 times, the whole operation being conducted by the steam of boiling water; 

 and the fluid is known to the trade as once, twice, or thrice run naphtha, 

 respectiA^ely. 



Here the legitimate labors of the tar-distiller end. He has prepared from 

 his black tar pitch, creosote, lampblack, naphtha, and sulphate of ammo- 

 nia. The first three are used, as we have already said, in their existing 

 forms; while the fourth, the coal naphtha, has yet to undergo a' greater 

 variety of changes, and to fulfil a larger number of offices, than all the other 

 products put together. 



In the state in which the naphtha leaves the tar-worker's yard, it is used 

 extensively for illumination, for which it is eminently fitted by the immense 

 amount of carbon it contains ; and if the lamp employed in burning it be 

 only constructed so as to allow of the actual combustion of this carbon, the 

 light emitted is probably greater than that obtained from the same bulk of 

 any other known substance. It is also a solvent of caoutchouc, gutta-percha, 

 and other gums, and therefore much in request by the varnish-maker; whilst 

 purified and deprived of its smell, by some secret method it becomes the 



