CARBONATES. 381 



Carbonate of soda, 37.5 or 1 proportion = 54 

 Water, - - 62.5 or 10 " =90 



100. 144 



(b.) 100 grains anhydrous carbonate neutralize 460 of sulphuric 

 acid, density 1.141; therefore supposing no other alkali present, as 

 460 to the acid required to saturate 1 00 grains of any sample of car- 

 bonate of soda, : : 100 to the quantity of anhydrous carbonate.* 



6. ACTION ON PRECEDING BODIES. 



Ja.) All that was said under the preceding article is true of this, 

 need not be repeated. 



(b.) Potassa decomposes this salt and renders the soda caustic, just 

 as the alkaline earths act upon the carbonate of potassa. 



(c.) Carbonate of soda, like carbonate of potassa, by double elec- 

 tive attraction, decomposes many salts, even sulphate of baryta, by 

 ignition. 



7. USES. 



(a.) Very valuable in the arts; in the manufacture of glass, es- 

 pecially of the finer kinds, which it renders more fusible ; of hard 

 soap ; in dying ; and as a detergent in washing and in bleaching ; but 

 for the two latter uses it must be rendered caustic. 



(b.) In soda water it is now extensively used as an antacid and 

 lithontriptic, fyc. and as an agreeable beverage. The watery solu- 

 tion of the salt is supersaturated with carbonic acid. It is prepared 

 in an iron bound barrel or a strong copper vessel lined with tin, fur- 

 nished with means of internal agitation ; the gas is injected by means 

 of a forcing pump ; four or five volumes of the gas are thus condensed 

 into one of water. Proportion of alkali, two ounces to ten pounds of 

 water, or from two and a half to three pounds, for a barrel. 



REMARKS ON SODA WATER. 



Having been concerned in the introduction of soda water, into this 

 country,| and having been much conversant with its manufacture 

 and use, I may be permitted to observe 



(a.) That if properly prepared, soda water is a very valuable 

 thing. To this end, the full proportion of soda should be dissolved 

 in ths water, and with the aid of cold, agitation and pressure, it 

 should be made to absorb carbonic acid as much as possible. This 

 will depend upon the strength of the machinery, and upon the well 

 known law, that if, as is the case with the carbonic acid gas, water, 

 at the common atmospheric pressure, absorbs an equal volume ; with 

 a double pressure it will absorb two volumes, with a pressure again 

 doubled, the absorption will again be doubled, that is, it will be four 

 times the first, and so on. 



* Henry, Vol. I, p. 565, 10th ed. t March, 1807. 



