IN POPULAR CHEMISTRY. 71 



3. IFJiat injury may be done by throwiny a small quan- 

 tity of H 2 O on a fire ? 



"No more heat is produced by the action of the H 2 O, but 

 it is in a more available form for communicating heat. The 

 steam in contact with incandescent charcoal is decomposed the 

 O going to the C to form CO 2 , and the H being set free. If 

 the C is abundant, and the heat high, the CO 8 is also decom- 

 posed, and double its volume of CO formed. The inflammable 

 gases, H and CO, mingled with the hydrocarbons always pro- 

 duced, are ignited, making the billows of flame which sweep 

 over a burning building." S. P. SHARPLES. 



4. IVliy does the hardness of ^vater vary in different 

 localities ? 



The hardness of the water will necessarily vary with the 

 solubility of the minerals in different localities. 



5. What causes the variety of minerals in the ocean ? 

 Is the quantity increasing ? 



The ocean contains the washings of the land. Every min- 

 eral soluble in water is borne to the sea. The quantity of min- 

 eral matter in the ocean would therefore seem to be increasing, 

 yet there is a compensation in the return to the soil, of guano, 

 marine plants, and fish, which are driven on shore by winds 

 and waves, or carried by the industry of man. 



Analysis of sea- water (Schweitzer) : 



Water 063. 74 



Sodium chloride 28.05 



Potassium chloride ... .76 



Magnesium chloride 3.66 



Magnesium bromide .02 



Magnesium sulphate 2.29 



Calcium sulphate 1.40 



Calcium carbonate , .03 



Iodine traces 



Ammonia traces 



1,000.00 



6. Is there not a compensation in the sea-plants, fish, 

 etc., which are washed back on the land ? 



(See Answer to Question 5.) 



