STARCH. 



171 



scale for local consumption. The method of preparing wood-tar 

 directly has already been described on page 147, and will again be 

 further noticed in Chapter IV. of Part III. Although wood-tar 

 can never compete with coal-tar in the general market, there is 

 still plenty of room for its more extended use in and near the 

 areas where deodar and pines grow. 



The method of dry-distilling wood will he explained under the 

 head of charcoal-burning in Part III. The acetic acid obtained 

 directly from the distillation is full of various other products, and is 

 in that condition termed pyroligneous acid. The pure acid is 

 separated in the "form of an acetate of lime, which is then heated 

 with sulphuric acid, or, better still, hydrochloric acid, the base 

 going to form sulphate or chloride, as the case may be, and setting 

 free the acetic acid. Acetic acid is a powerful solvent of various 

 organic bodies, camphor, resins, essential oils, phosphorus, &e. It 

 is extensively used in the treatment of gums, caoutchouc, and 

 various albuminous substances, in the manufacture of paints and 

 varnishes, and as a drug. The uses of vinegar are well-known. 

 The crude pyroligneous acid, owing to its containing creosote 

 and other hydro-carbons, is a powerful antiseptic. Finally, acetic 

 acid forms a series of salts, or " acetates," of special value in calico 

 printing, dyeing, and other branches of industry. 



Wood alcohol is, however, the most important product of the dry 

 distillation of wood and constitutes about 1 per cent, of the distillate. 

 Combined with sugar alcohol in the proportion of 10 parts to 90 

 of the latter, it becomes the methylated spirits of commerce, a 

 product of such wide use in the arts and manufactures and in the 

 scientific laboratory. Bleaching powder acting upon wood spirits 

 produces chloroform. Ether is prepared by heating alcohol with 

 sulphuric acid. 



The products of the dry distillation of wood comprise, besides the 

 substances already mentioned, all the substances, such as paraffin, 

 benzene, Ac, yielded in much larger quantities and at infinitely 

 less expense by the distillation of coal. 



Section III. — Staech. 



The only woody Indian species from which starch is extracted 

 are a few palms, such as Caryota urens, Phmnix dcaulis, Arenga, 

 and Corypha. This starch is, however, only consumed locally 

 and has practically no market value. But there is no reason why 

 it should not become an article of trade. Owing to the peculiar 

 structure of the stems of palms, the centre consists entirely of 

 cellular tissue rich in starch, the quantity of which is generally 



