Intelligence and Miscellaneous Articles. 473 



In the first case the lamina of glass employed transmitted 0*44 of 

 the incident heat ; in the second only 0-33 to 0'34. 



These two methods afford then concordant results ; and the 

 authors are of opinion that they have determined that, on a great 

 number of metals, and probably on all, the different kinds of heat 

 are reflected unequally, and that the reflexion on polished metals 

 changes the j)roportions of the different kinds of heat which compose 

 the incident bundle. — Comptes Rendus, Avril 16, 1849. 



ON CHLORONICEIC ACID. BY M. E. SAINT-EVEE. 



For the preparation of this acid, the first operation consists in 

 passing a current of moist chlorine gas into a cold and strongly alka- 

 line solution of benzoate of potash. After many trials, the propor- 

 tions which succeeded best were found to be 60 grms. of benzoic 

 acid, 200 grms. of hydrate of potash, and 300 to 350 grms. of water, 

 according to the degree of hydratation of the potash of commerce, 

 which is far from being constant. 



The potash is to be dissolved at a gentle heat, and the benzoic 

 acid afterwards added ; and the chlorine is not to be passed till 

 everything is dissolved. After some time the solution assumes suc- 

 cessive shades of yellow, greenish-yellow and bright green ; it then 

 again becomes yellow, and eventually deposits an abundant pulpy 

 compound, which is grayish and crystalline. An abundant evolution 

 of carbonic acid takes place during the operation, which is readily 

 detected by passing it into a vessel containing barytes water. An 

 operation performed with the quantities above described continues 

 about two days. 



The precipitate is composed, — 1st, of chlorate of potash, the cry- 

 stallization of which is completely modified by the presence of or- 

 ganic matter, the salt being usually obtained in the form of four- 

 sided prisms ; they are long, hard and brittle ; 2nd, of a small quan- 

 tity of unaltered benzoate of potash ; 3rd, of a salt of potash con- 

 taining the new acid ; and lastly, the supernatant liquor contains 

 benzoate of potash and chloride of potassium. 



About half its volume of water is to be added to the mass. The 

 solution is to be saturated, at a moderate temperature, by means of 

 a current of carbonic acid, the saturation being completed by the 

 addition of a small quantity of dilute hydrochloric acid. The solu- 

 tion is then to be boiled. The magma which is precipitated gra- 

 dually redissolves, and there soon appears an oleaginous substance 

 which is fusible at about 270° F. ; it is of an amber colour, and heavier 

 than water. It sometimes precipitates to the bottom of the capsule, 

 and sometimes, on the contrary, it floats, according to the degree of 

 concentration of the solution. The solution being poured off, an 

 oily matter remains, which soon concretes by cooling. 



The crude acid thus prepared is hard, brittle, of a slight yellow 

 colour, and contains a notable quantity of benzoic acid. It is freed 

 from this by repeated solutions in boiling distilled water ; and the 



