1839.] 



On Chemical Tests, 



293 



former deflagrates on applying sufficient heat, but neither of them ful- 

 minates like the oxalate of silver. 



16. ACID prussic; see 10. 



17. ACID phosphoric is detected by proto-nitrate of mercury which 

 produces a precipitate, of phosphate of mercury ; by acetate of lead 

 Which gives a white precipitate ; and by nitrate of silver which yields 

 a yellow precipitate. All these precipitates are soluble in nitric acid. 

 No alkali, or alkaline earth should be present, see 83 e. The detection 

 of phosphoric acid is frequently attended with difficulty. 



a. Solutions of the neutrnl phosphates of alkalies produce precipi- 

 tates with the muriates of barytes, and lime; and with lime water and 

 barytes water. These precipitates are soluble in muriatic and nitric 

 acids ; and in solutions of ammoniacal sal ts. 



18. ACID sulphuric, (see 116) detects («). The acids in combina- 

 tion with salts; (b), barytes; (c), strontian ; (d), lime; (<?), lead; 

 (/), mercury; (g), carbonic acid; (h) vegetable or carbonaceous 

 matter. 



a. The salt to be examined should be in the solid state or near- 

 ly so : it is to be pounded and covered with sulphuric acid, and 

 heat is then to he employed. If the salt is a nitrate, the nitric acid 

 will be evolved in white vapours without effervescence, and if 

 copper filings be added, red vapours accompanied with effervescence 

 will be disengaged. See 14. If the salt be a muriate, the muriatic 

 acid will be driven off in white vapours, which will form a dense white 

 cloud round a rod held in them, if it be first dipped in ammonia. See 11 d, 

 28 b. Acetic acid will be discovered by the vapours smelling like 

 vinegar, see i. Fluoric acid is driven off in poisonous fumes, which 

 must not be inhaled, and which corrode glass if it be held in or over 

 them for a few minutes, see 54. The whole of the foregoing indica- 

 tions may be confirmed by other tests. 



b. Baryta detects and is detected by sulphuric acid either free, or in 

 combination, as in the state of sulphates, by the production of a white 

 precipitate, see 40, and 115 e. 



c. Stronlia is affected in the same manner as barytes, see 40, and 115. 



d. Lime is detected by sulphuric acid, but the solution should be 

 concentrated, — oxalate of ammonia is a better test for lime, see 35,44,72. 



e. Lead gives a white precipitate of sulphate of lead, when tested 

 with sulphuric acid, see 60. 



