185Y.] The Raw Material. 203 



Carbonate of Lime (Lime Stone) Cai'bonate of Magnesia, Carbonate 

 of Potash, Chloride of Sodium (common Salt) Chloride of Potasium, 

 Sulphate of Lime, Phosphate of Lime, Silica, Sesquioxide of Iron, 

 Soda, Oxide of Manganese, Carbonic Acid, and Organic matter con- 

 taining Ammonia. 



"Well water," says Johnson in his admirable work "the Chemistry 

 of Common Life," "sometimes contains, vegetable substances of a pe- 

 culiar kind, which render it unwholesome even over large tracks 

 of country. In sandy districts, the decaying vegetable matters of the 

 surface soil are observed to sink down, and form an ocherypavi; or, 

 thin yellow layer in the subsoil, which is impervious to water and 

 through which therefore the rains can not pass. Being arrested by 

 this pan, the rain water, while it rests upon it, dissolves a certain por- 

 tion of the vegetable matter ; and when collected into wells, is often 

 dark colored, marshy in taste and smell, and unwholesome to drink. 

 When boiled, the organic matter coagulates, and when the water cools 

 separates in flocks, leaving the water wholesome, and nearly free 

 from taste or smell. The same purification takes place when the wa- 

 ter is filtered through charcoal, or when chips of oak wood are put 

 into it. These properties of being coagulated by boiling, and by the 

 tannin of oak wood show that the organic matter contained in the 

 water is of an albuminous character or resembles the white of eggs. 

 As it coagulates, it not only falls itself, but it carries other impurities 

 along with it and thus purifies the water, in the same way as the 

 white of eggs clarifies sugar and liquors to which it is added. The 

 waters of the Seine, at Paris, are clarified by introducing a morsel of 

 Alum ; and the river and marshy waters of India, by the use of the 

 nuts of the strychnos potatorum of which travelers often carry a 

 supply. One or two of these nuts rubbed to powder on the side of 

 the earthen vessel into which the water is to be poured, soon causes 

 the impurities to subside. In Egypt, the muddy water of the Nile 

 is clarified by rubbing bitter almonds on the sides of the water ves- 

 sel in the same way. 



In all these instances the principle of clarification is the same ; the 

 albuminous matter is coagulated by what is added to the water, and 

 in coagulating, it embraces the other impurities of the water and 

 carries them down along with it." 



Water is composed of two gases. Oxygen and Hydrogen, in the 

 proportion by weight of one of the latter. Oxygen is that gas found 



