USEFUL PRODVCTS FROM COAl., ^4J 



No. 1. is what came oiF the tar first. No. 2. is the same Rectiikatioo ©i^ 

 distilled a second time: and the third specimen is the se-*^^^^^^ 

 cond redistilled again in a glass retort; it there leaTes a 

 little pitchy residuum, and comes oyer clear, as the sample. 

 Very little of the spirit is lost in passing through these dif. 

 ferent stages, if care is taken, that the fire is slow, and 

 the process not hurried. When the spirit is perfectly ex^ Aspbaltism, 

 tracted from the tar, there remains in the basin of the re- 

 tort that beautiful pitch or asphaltum sent; which, when 

 mixed with the spirit, forms an ingredient for making (he 

 black varnish used in japanning. If it is wished to use itPwcJj. 

 as pitch, less spirit must be extracted from it. I find, that 

 six gallons of tar will produce, if care is taken, about two 

 gallons or two gallons and a half of spirit. A great num- 

 ber of retorts may be kept working by a single man; if we 

 say only one hundred, and only worked down in a day, 

 they will produce from two hundred to two hundred and 

 fifty gallons of spirit, so that by increasing the number, 

 any quantity may be obtained. When the spirit is used in 

 the place of turpentine, the varnish. maker uses it in the 

 same way, and in the same quantity, as there appears no 

 manner of difference in the use of it from the spirit of 

 turpentine in the making of varnish. When the asphaltun^ 

 is used, it supplies the place of real asphaltum, and in 

 about the same quantity. I have explained the whole as 

 clear as I can, but if any more information is required, I 

 should feel happy in giving it, and am. 



Sir, With great respect, 



Your obedient humble servant, 



B. COOK. 

 *^* To such persons as wish for further particulars on Lighting apart- 

 the subject of lighting apartments with gas, it may be pro- "*^"^* ^i^^ S^^ 

 per to note, that the society, in their 26th volume of 

 Transactions, page 202, have given an engraving and de- 

 scription of a gazometer, and apparatus for making car- 

 bonated hidrogen gas from pit coal, which communication 

 was sent to them by Mr. S. Clegg, of Manchester*. 



* See Journal, vol. xxiii, p. 85. See also two original commu- 

 nications by Mr. Cook on the advantages of coal gas lights, even 

 on a very small scale : vol. xxi, p. 291, and xxii, p. 145. 



III. Method 



