526 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



sons. It may, therefore, be interesting to know of a method 

 which, according to Professor Church, will entirely remove 

 this odor, substituting for it a delicate trace of geranium 

 leaves, which may, perhaps, be improved upon by adding a 

 few drops of that oil. The process, as recently published by 

 Mr. Church, consists in pouring one pound of the best carbolic 

 acid of commerce (the white crystallized) into two gallons 

 of cold distilled water, taking care not to permit the whole of 

 the acid to enter into solution. With a good sample, if, after 

 shaking repeatedly at intervals, between two and three ounces 

 of the acid remains at the bottom of the vessel used, this will 

 be a sufficient residue to hold and contain all the impurities; 

 with bad samples, less water must be used, and more acid. 

 The watery solution is to be sij)honed off, and filtered, if nec- 

 essary, through fine filter-paper till perfectly clear. It is then 

 placed in a tall cylinder, and pure powdered common salt 

 added, wjth constant agitation, till it no longer dissolves. 

 On standing for a time, the greater part of the carbolic acid 

 will be found floating as a yellow oily layer on the top of the 

 saline liquor, and merely requires to be removed to be ready 

 for use. As it contains five per cent, or more of water, it does 

 not generally crystallize, but it may be made to do so by dis- 

 tilling it from a little lime. The portion collected, up to 

 about 365 Fahr., has, at ordinary temperatures, scarcely any 

 odor save a faint one resembling that of geranium leaves. 

 The addition of about four drops per fluid ounce of the French 

 oil of geranium will still further mask the slight odor of the 

 acid, and has an additional advantage of liquefying the pure 

 crystallized product. The pure acid may be dissolved in 230 

 parts of water and used as a gargle, or in 25 parts of water 

 for painting the throat, or in 50 parts for the carbolic Bpray. 

 20 A, October 21, 1871, 502. 



INTERMITTENT ELECTRIC LIGHT FOR SIGNALS. 



Mr. Felix Lucas, a French engineer, proposes to obtain a 

 very powerful electric light for coast service at a compara- 

 tively small cost, by making the light intermittent, with in- 

 tervals of two seconds. By this means it is said that only 

 one ten thousandth part of the electricity for a constant light 

 will be required. A simple arrangement of clock-work causes 

 the charcoal points to come in contact every two seconds, 



