1339.] On Chemical Tests. 279 



phuric acid. Then mix with it some alcohol, and inflame it : if a green 

 flame is produced, the acid in combination is boracic acid. 



liv. t. If neither fluorine, nor boracic acid be present, add to the 

 acid solution of the substance liquid sulphuretted hydrogen, and boil 

 it: if a yellow precipitate is formed, soluble in hydrosulphuret of am- 

 monia, it indicates arsenic acid.* 



Carbonic acid, Lv . M> When it has been ascertained that none of the 



bulpnuric acid, 



Boracic acid, foregoing substances are present, add to a portion of the 



Arsenic acid, .... 



Phosphoric acid, substance dissolved in dilute nitric acid, nitrate of sil- 



Sulphur, ... . , 



Fluorine. ver ; and if a white precipitate is produced, winch is 



not soluble in dilute nitric acid, but which is soluble in ammonia, then 

 the substance contains chlorine in combination with one of the bases 

 before enumerated. 



lvi. Lastly, if none of the foregoing substances have been discover- 

 ed throw a portion of the pulverized mineral on red hot charcoal. If 

 lively combustion occurs, or if deflagration takes place, the acid in com- 

 bination is nitric acid. 



lvii. Note. As before observed, each paragraph beginning with 

 a letter, i. e. from a to u, details a distinct experiment, which is to be 

 performed with a fresh and distinct portion of the substance in solution, 

 as directed; except the last experiment (lvi) in which the mineral or 

 substance is to be pulverized. 



OBSERVATIONS. 



lviii. The foregoing detailed experiments suppose that the nature of 

 the substance is wholly unknown to the experimentalist; but whether 

 it is "partially known or not, he should assure himself of the accuracy of 

 his determinations by other tests w hich he will find in the following pages. 



Lix, In using the alphabetical list of tests, it will be frequently 

 seen that several tests act on the metal, or substance to be tested. 

 The learner may be at a loss which test to choose : but in those cases 

 where the test is distinctive, its indications are printed in italics; by 

 running the eye therefore over any article, wherever the indications 

 of the tests are seen printed in italics, those tests are to be preferred, 

 as being those lohich may be most relied on. 



lx. When testing, it is desirable, in almost every case, to refer 

 to the tables of tests at the end of this paper in order to ascertain at 

 a glance how other tests affect the substance tested. This should never 

 be neglected by the inexperienced. 



* If neither sulphuric, arsenic, boracic nor fluoric acid is present, then the precipi- 

 tate (l. s) must prove to be the only remaining acid, viz. the phosphoric. 



