116 THE ALUMNI JOURNAL 



For many grades of castings an addition of a small amount of 

 sulphuric acid to the hydrofluoric acid has been found desirable. The 

 amount added is not enough to attack iron rapidly, but it does loosen 

 a portion of the scale and sand and allow it to drop away without being 

 acted on by the hydrofluoric acid, so saving the latter. Our chemists 

 have prepared a mixture which is particularly suitable and we will 

 market it under the name of Flourine Pickle. Of course, we can 

 supply the pure acid and special mixtures when desired. 



From Things Chemical. 



BENZIN, NAPHTHA AND GASOLINE/ 



By Otto Raubenheimer, Ph. G., 

 Brooklyn, N. Y. 



Much confusion exists in regard to the products termed respectively 

 benzin, naphtha and gasoline. I have repeatedly sent to paint stores 

 and even to drug stores and asked for gasoline and received instead 

 ordinary benzin. When I would return it as not the fluid asked for 

 I would be invariably told that it was "all the same." 



Benzin, naphtha and gasoline may be compared to 94 per cent, alco- 

 hol, deodorized alcohol and absolute alcohol. If a customer asked for 

 absolute alcohol the pharmacist would not think of giving him 94 per' 

 cent, alcohol in place of it, but the very satue pharmacist would have 

 no hesitation about dispensing benzin for gasoline. Of course, he 

 might make the argument that gasoline was too explosive and too 

 highly inflammable, and therefore too dangerous, to use. The cus- 

 tomer, however, ought to be told these facts and warned not to use it 

 in a room in which a light is burning. For cleansing purposes it is 

 best to use it outdoors. In addition, a red danger label ought to be 

 attached to the container. 



Let us consider for a moment the difference between benzin, naph- 

 tha and gasoline. When crude oil is subjected to fractional distilla- 

 tion the verv lightest hydrocarbons distil over first, the product be- 

 ing called gasoline. The next distillate, of a heavier specific gravity, 

 is naphtha, and the next heavier is benzin, the last and heaviest being 



kerosene. 



The specific gravity of these liquids is ordinarily taken with a 

 Baume hydrometer for liquids lighter than water, or what is called 



1 Presented to the American Pharmaceutical Association, 1905. 



