Analysis of the Pittsburgh Mineral Spring. 127 



6. Nitrat of silver. — When a few drops of this test are ad- 

 ded to a glass of this water, a dense white flocculent precipi- 

 tate is thrown down, which after some time changes to a light 

 purple color. 



7. Acetate of lead, throws down an immediate dense white 

 precipitate, the color of which is rendered a shade darker 

 when allowed to stand in the glass for a few hours. This 

 precipitate is partly dissolved when a few drops of nitric 

 acid are poured on it, which shows that a small quantity of 

 sulphuric, as well as muriatic acid, is present ; muriat of 

 lead being soluble, while the sulphate is perfectly insoluble 

 in any acid. 



8. Muriat of Barytes, produces a white cloud when per- 

 mitted to stand for some time, a precipitate falls which is not 

 soluble in nitric acid. 



9. Oxalat of Ammonia, produces a slight turbidness but 

 scarcely any precipitate. 



10. Liquid or pure ammonia, has no effect on the water either 

 when fresh from the spring or when concentrated by boiling. 



1 1 . Carbonat of potash, does not disturb the transparency 

 of the water. 



1 2. Sulphuric acid. — This acid produces no change. 



SECTION II. 



Inferences to be drawn from the above experiments. 



If it was only required to determine the quality of this 

 water, and the nature of the ingredients, these experiments 

 would be nearly sufficient ; but no chemical investigation 

 will be deemed satisfactory at present which does not exhi- 

 bit the exact proportions of the different ingredients. Be- 

 fore however we proceed farther in the investigation, the use 

 of tests and reagents become an important guide ; by their 

 means future experiments may be conducted with more pre- 

 cision, and when we proceed to evaporation, much time 

 and labour are spared in looking for those substances which 

 we had previously ascertained by reagents not to be present. 

 Thus having discovered iron by experiments 4 and 5 and 

 that it is held in solution bv carbonic acid, it was in vain te> 



