606 Intelligeyice and Miscellaneous Ai tides. 



For arsenious acid. — Lime water in excess produced a precipitate 

 in a solution containing l-4000dth of this acid. 



Ammoniacal solution of oxide of copper detected l~8000dth. 



Sulphate of copper and ammonia detected l-12,000dth. 



The two last reagents occasioned precipitates in still more diluted 

 solutions, hut the precipitates did not possess their characteristic 

 green colour. 



Hydrosulphuric acid produced a precipitate in 1 - 30,000dth. 



Ammonia nitrate of silver formed a yellow precipitate with 

 l-30,000dth ; with a more diluted solution the colour of this preci- 

 pitate was not sufficiently apparent. 



3. The sensibility of reagents /or metals and their oxides. 



For free alkalies in general. — Turmeric paper detected the pre- 

 sence of l-3000dth caustic alkali. 



Paper stained with red cabbage detected the presence of 

 l-7500dth caustic alkali. 



Brazil wood paper was coloured slightly violet with 1 -20,000dth. 



Litmus paper reddened by acetic acid was distinctly rendered blue 

 by l-80,000dth. 



Hydrate of potash contains 1 6 per cent, of water, therefore the 

 quantity of real potash detected by the above reagents was 

 l-3600dth, l-9000dth, l-24,000dth, and l-95,000dth. 



For potash. — An alcoholic solution of chloride of platinum occa- 

 sioned a precipitate in a solution of nitrate of potash containing 

 l-205th of this base; a solution containing l-200dth was not pre- 

 cipitated by it. 



A very concentrated solution of tartaric acid produced a precipi- 

 tate with 1 -220th, but none with 1 -230th, The sensibility of these 

 reagents was tried at a temperature of 59° F. 



For lime. — Oxalate of ammonia produced a cloudiness after a few 

 minutes in a solution of chloride of lime containing l-400,000dth 

 of lime. 



For baryta. — Fluo-silicic acid produced a slight precipitate in a 

 solution of chloride of barium containing l-3800dth of baryta. 



A solution of sulphate of soda produced in half an hour a cloudi- 

 ness in a solution containing l-71,000dth. 



For magnesia. — A solution of phosphate of soda indicated in 24 

 hours the presence of l-200,000dth of magnesia in a solution of sul- 

 phate of magnesia. This reagent must be very concentrated, and 

 a quantity equal to the solution examined, must be added. These 

 conditions are absolutely necessary, as otherwise this reagent will 

 not indicate the presence of even 1-lOOOdth magnesia in solution. 

 This is probably the reason that M. Roth fixes the delicacy of this 

 reagent at 1 -4000dth of magnesia. 



A solution of ammonia produced after some minutes a slight pre- 

 cipitate in a solution containing l-6000dth of magnesia. 



For protoxide of iron. — Tincture of galls and a solution of ferro- 

 prussiate of potash, acidulated with a few drops of hydrochloric acid, 

 indicated after some minutes the presence of protoxide of iron in a 

 solution containing l-440,000dth of crystallized sulphate of iron. 



