Intelligence and Miscellaneous Articles. 605 



23 to 25. Containing l-450,000dth to l-550,000dth iodine, the 

 upper stratum of the precipitate was slightly rose-colour, the under 

 stratum was white. 



The action took place immediately on the addition of the starch 

 as far as No. 19. The following numbers required some period to 

 elapse first : it required some hours in the solution of l-500,000dth 

 to l-550,000dth before any effect was produced. 



2. The sensibility of reagents on acids. 



For sulphuric acid, specific gravity 1'829, containing 75*S3 per 

 cent, real acid. 



Syrup of violets did not detect less than 1- 250th sulphuric acid 

 of the above specific gravity, or l-310th real acid. 



Paper stained by Brazil wood was acted upon by l-10,000dth, 

 or l-r2,500dth real acid. 



Paper stained by tincture of red cabbage was reddened by 

 l-15,000dth, or l-18,750dth real acid. 



Paper stained by logwood was changed to a golden yellow colour 

 by l-50,000dth, or l-62,500th real acid. 



Paper stained by litmus was immediately reddened by 1 -20,000dth, 

 or l-25,000dth real acid, and after some hours was slightly reddened 

 by l-50,000dth, or l-62,500dth real acid. 



Carbonate of potash occasioned a slight effervescence with 1- 

 250th, or 1-3 10th real acid. 



For phosphoric acid. — Brazil wood paper and paper stained 

 with red cabbage detected l-10,000dth of anhydrous phosphoric 

 acid. 



Litmus paper was immediately reddened by l-10,000dth, and 

 after some hours by l-30,000dth phosphoric acid. 



Peculiar reagents for various acids. 



For free sulphuric acid. — A concentrated solution of chloride of 

 calcium occasioned a precipitate, after some hours, in a solution 

 containing l-310th of real sulphuric acid. 



A solution of acetate of lead gave a precipitate with l-50,000dth 

 real acid. 



A solution of chloride of barium gave a precipitate with 

 l-75,000dth. 



For combined sulphuric acid. — Acetate of lead produced a pre- 

 cipitate in a solution of sulphate of soda containing l-36,000dtli 

 acid. 



Chloride of barium in a solution of the same salt containing 

 l-45,000dth acid. 



For nitric acid — By means of hydrochloric and gold leaf 1 -240th 

 of nitric acid, spec. grav. r32 was detected : the gold leaf was dis- 

 solved in 24 hours. 



For phosphoric acid. — Acetate of lead produced an immediate 

 precipitate with l-10,000dtli anhydrous acid, and with l-20.000dth, 

 after remaining for half an hour. 



Lime water j)roduced exactly the same effect. 



Chloride of barium did not occasion a precipitate in less than 

 1-I0,000dth. 



