114 FINE CHEMICALS AND PHARMACEUTICS. [IV. 



and a few for the artisan. They are alkaline, earthy, and 

 metallic compounds, metalloidal compounds, organic acids and 

 alkaloids, &c. These may be conveniently divided into inor- 

 ganic and organic. 



1. Inorganic Bodies. — We find a few observations in re- 

 ference to some of the metalloids, &c., which are here inserted. 



Clilorine Prejyaration. — Over 1 pt. bichromate of potassa 

 in a flask, pour 6 pts. muriatic acid of 1.16, and gently heat 

 the mixture for a few seconds by a spirit lamp. A rapid ac- 

 tion ensues, resulting in the evolution of chlorine and the 

 formation of water, chlorides of chrome and potassium. 

 (Amer. Journ. c. 491.) 



Quantitative Determination. — Cottereau proposes for this 

 purpose a solution of protochloride of tin (of known content) 

 colored by sulphate of indigo, to which the chlorine-liquid is 

 added until decolorization commences. From the volume of 

 the latter employed, the quantity of chlorine is calculated. 

 The free chlorine changes protochloride into perchloride of tin. 



Iodine, its Extraction. — Pass sulphurous acid into a mineral 

 water, or other liquid, containing iodine, until it has acquired 

 a feeble odor of the same ; then dissolve it in 1 pt. blue vitriol, 

 and, after it, 1 pt. bisulphite of soda ; white or rosy subiodide 

 of copper will precipitate immediately by boiling, or in a short 

 time by standing. If the precipitate be mixed with 2 equiv. 

 binoxide of manganese and heated, iodine sublimes. 



Chloride of Iodine. — Heeren recommends the use of chloride 

 of iodine in photography instead of bromine compounds, which 

 are more subject to alteration, and offers the following method 

 of preparing it. 200 gr. dilute sulphuric acid (1 acid to 5 

 water) are poured over 100 gr. iodine, and dry chlorine gas 

 passed through until the increase of weight is QQ gr. which 

 must be accurately ascertained. The chlorine should be pre- 

 viously passed over chalk and chloride of calcium to remove 

 water and muriatic acid from it ; and the end of the tube 

 conveying the gas should be about a J inch above the surface 

 of the liquid. The dark-orange liquid should be kept in a 

 well-stoppered bottle, in a dark place. When used, 1 pt. of the 



