n6 ARTIFICIAL PRODUCTION PAKT i. 



from that originally in view, which have had unexpected 

 and invaluable results. Although the simple elements 

 are few, they are capable of an infinite variety of com- 

 binations, so that by analysis and new combinations, 

 the most useful and valuable materials are now ob- 

 tained from obnoxious or useless substances, formerly 

 thrown away. The instances are numerous ; but saw- 

 dust may be mentioned as one of the most remark- 

 able. It was not even fit for fuel, but now oxalic acid, 

 a bleaching principle most extensively used in the 

 various processes of calico printing, is procured from it ; 

 the quantity required may be imagined, since the cotton 

 cloth annually printed in Great Britain previous to the 

 American war, would surround the earth's equator 

 nineteen times. Oxalic acid, which is a vegetable sub- 

 stance, found combined with potash in wood sorrel or 

 Oxalis acetosella, used to be made from sugar or starch, 

 by the action of nitric acid. Now starch, sugar, and 

 ^ woody fibre or^bsme, all contain twelve parts of carbon 

 and different portions of oxygen and hydrogen, always 

 in the proportions that form water ; hence the name of 

 carbohydrates. Their composition is so similar that 

 the one may be changed into the other by the addition 

 or subtraction of one or two atoms of water under its 

 atomic form ; thus when fruits ripen, the starch they 

 contain is changed into sugar by the addition of one 

 atom of water under its dry form. 



Now sawdust is woody fibre, and might be changed 

 by nitric acid into oxalic acid like the others. But a 

 less expensive method is actually employed. 



When sawdust, mixed with two equivalents of the 

 hydrate of soda and one equivalent of the hydrate of 

 potash, is exposed to a heat of 400 for a few hours, the 

 substances are fused, and when raised to a still higher 

 temperature the hydrates are decomposed : hydrogen is 

 evolved, and the carbon combines with the oxygen to 



