cnEMiSTriY. 229 



Alcolwlfrom Wood. — In tho process of makinir paper from wood, 

 as practised in Europe, round disks of wood are first suojcctcd to 

 the action of hydrochloric acid to dissolve the spongy cellulose. 

 Tliis latter has, until lately', been a waste product, hut is now con- 

 verted into alcohol in this wa}' : The wood is boiled for 12 hours 

 in hydrochloric acid, diluted with 10 times its volume of water. 

 The acid liquid, which is charged with grape sugar formed from 

 the spongy cellulose, is then withdrawn, the excess of a(;id satu- 

 rated witli lime or chalk, and a small quantity of yeast is added, 

 the temperature being kept at about 68° F. Fermentation soon 

 ensues, and when bubbles of carbonic-acid gas are no longer 

 evolved, the liquid is distilled to obtain the alcohol. 



Gas-proof Cement for Laboratories. — SorePs cement of basic 

 chloride of zinc, when properly applied, is safer and better than 

 the common lutings employed for preventing the escape of nox- 

 ious gases, as, for instance, in the preparation of chlorine. For 

 this purpose, commercial zinc-white is mixed in a mortar with 

 one-half its bulk (or an equal weight) of fine quartz sand, and 

 then rubbed up with an equal weight of chloride of zinc solution 

 of 1.26 specific gravity (30° Baume). — Dingler''s Journal. 



Harmless " Pharaoli's Serpents.^'' — A new method of making the 

 chemical toys called Pharaoh's Serpents has been suggested by 

 Vorbringer. The black liquor, which results as a useless product 

 when coal oil is purified with sulphuric acid, is treated with fu- 

 ming nitric acid. The dark-colored resinous matter which swims 

 on the surface is then collected, washed and dried, when it forms 

 a yellowish-brown mass, having about the consistency of sulphur 

 which has been melted and poured into water. When this is ig- 

 nited it undergoes such a wonderful increase in bulk that a cylin- 

 der 1 inch long will give a snake about 4 feet in length. 



Chloride of Silver. — Prof. Morren has observed some curious 

 reactions of chloride of silver w^hen in presence of chlorine. 

 Moist chloride of silver recently prepared with an aqueous solu- 

 tion of chlorine, when enclosed in a glass tube, gradually becomes 

 blackened when exposed to light, silver being reduced and chlo- 

 rine liberated. On the sealed tubes being placed in darkness, the 

 liberated chlorine would recombine with the silver, again forming 

 white chloride of silver. This decomposition and recomposition 

 might be effected indefinitely. So also of bromide of silver and 

 other salts. 



Test for a Free Acid. — Dissolve chloride of silver in just sufii- 

 cient ammonia to make a clear solution. If a little of the test be 

 added to ordinary spring-water, the carbonic acid present in the 

 latter will neutralize the ammonia and precipitate the chloride. 

 The above forms a good lecture experiment, the test being a very 

 delicate one. 



To Remove Aniline Colors. — Instead of powdered metallic zinc, 

 which simply converts them into compounds of zincaniline, with- 

 out alwavs rendering them soluble in water, Dangeville and Gau- 

 tin employ a solution of permanganate of potash, with some di- 

 lute sulphuric acid, thickened, if required, by clay or gelatinous 

 silica, and followed by a bath of sulphurous acid. 

 20 



