M. TECHNOLOGY. 555 



aration commences immediately; and, without the necessity 

 of interfering with it at all, the petroleum, with all its original 

 properties, very soon re -appears, clear and limpid, floating 

 above the watery extract which occupies the bottom of the 

 vessel. It is calculated that at the expense of about $3 per 

 100 pounds, for which sum the soap-wort can be purchased, 

 the increase in the price of the petroleum consequent upon 

 the employment of this process will be almost inappreciable. 

 d BjJitli/ 25, 1812, 598. 



PETEOLEUM OILS AND CAEBOLIC ACIDS. 



Petroleum and the many products derived from it are at 

 present so extensively used that it is of great importance to 

 have a fixed standard by w^iich to judge their money value, 

 as well as their applicability to the intended purpose. The 

 light oils, or so-called naphthas, greatly differ in their degree 

 of volatility ; while safety and efficiency in their manifold ap- 

 plications frequently depend on this quality. In order to 

 secure consumers against deception, a large chemical estab- 

 lishment, in Brunswick, has divided these naphthas into five 

 classes, ranging from a specific gravity of 0.65 to 0.75, and a 

 boiling-point from 104 to 338 Fahr. The quality in every 

 case is guaranteed, and the price conforms to it. The value 

 of carbolic H-cid now so much in demand as a disinfectant 

 depends on the amount of phenol contained in it, which 

 is very variable in different specimens. The same manufac- 

 turers accurately ascertain the percentage of phenol in their 

 products, and regulate the price absolutely in proportion, so 

 that a hundred-weight of carbolic acid with 100 per cent, of 

 phenol costs about $12; while the same quantity, containing 

 only twenty per cent, of phenol, is sold for about $2 50. By 

 thus giving definitely the amount of the active principle, the 

 economical and successful use of the article is greatly facili- 

 tated, and the practice of demanding a certain price for the 

 mere name of a thing irrespective of its intrinsic value is 

 done away wdth. 8 C, 1872, xxix., 232. 



AQUEOUS SOLUTIONS OF SHELLAC. 



According to Walzan, an aqueous solution of shellac may 

 be made by breaking it up and covering it with a concen- 

 trated solution of carbonate of ammonia, boiling it upon a 



