CHEMISTRY. 203 



tlie Oak Orchard Spring, N. Y., for instance, is very rich in the 

 free aeiil. 



4. Waters from lime regions all contain lime in large quan- 

 tities, and, in fact, this is the most common impurity of spring 

 waters. 



5. Iron is contained in large quantity in the so-called chalyb- 

 eate springs; also copper and other metals are encount(3red ; 

 lt?ad incidentally, bj'^ the lead tubes through which it often is made 

 to pass. 



6. Carbonic acid is the most common impurity ; even distilled 

 water is not always free from it. Water will naturally absorb 

 carbonic-acid gas from the atmosphere, which always contains it; 

 its principal source of supply being derived from the exhalations 

 of man and animals. 



7. Organic substances are often found in the water of running 

 brooks, streams, and rivers, and are of course obtained from the 

 vegetation and animal life in the water itself, and from the shores 

 along which it floats. 



Remarks. — 1. The healthfulness of water depends on the 

 nature of the residue left after evaporation; for many chemical 

 and other operations, where absolutely pure water is required, 

 the leaving of residue at once proves the water unfit for use. 



2. The existence of small quantities of common salt in the 

 water is not objectionable, it being not injurious to health. 



3. Sulphuric acid and sulphates may be objectionable for daily 

 use ; however, such waters are used medically to stop diarrhoea 

 and excessive tendency to perspiration. 



4. Lime waters do not agree with some constitutions, producing 

 diarrhoea and diverse disturbances ; very small quantities of lime, 

 however, are not injurious. 



5. Iron is healthy, and is a tonic ; in fact, this metal and man- 

 ganese are the only ones which may be used in large doses, not 

 only with impunity, but even with benefit ; however, there is also 

 a limit. Over doses of iron may produce diarrhoea and slight 

 eruptions of the skin, or pimples. 



6. Carbonic acid is not objectionable when drinking the water; 

 on the contrary, it makes it more palatable, and most mineral 

 waters owe their reputation to this substance. 



7. Organic substances are perhaps the most objectionable, 

 jorincipally when decaying ; such waters may even propagate 

 diseases, and require careful filtering or boiling, or both, to make 

 them fit for internal consumption. — Scientific American. 



DANGERS FROM KEROSENE. 



At a recent meeting at the Massachusetts Institute of Technol- 

 ogy, Mr. Frederic E. Stimpson, Secretary of the '* Committee on 

 Chemical Products and Processes," made the following report in 

 behalf of that committee, on the subject of the "difference be- 

 tween the volatile hydrocarbons known in the market as gasoline. 



