ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 85 
tragacanth in a similar quantity. After a few hours the tragacanth 
solution is shaken until it froths, and then mixed with the gum arabic 
solution. The mixture is strained through linen, and 150 grm. of 
glycerin (previously mixed with 2J grm. of oil of thyme) added to it. 
Cement for Porcelain.* — The Chinese cement for porcelain (schio- 
liao), glass, and such like articles, is composed of finely powdered 
calcined lime 54 parts, alum 6 parts, fresh blood 40 parts. These 
ingredients are worked up into a homogeneous mass. Pasteboard or 
paper articles saturated with a dilute form of this cement, made by 
thinning it down with water, become as hard as wood. Diluted, it may 
be used to give a protective coat to walls of rooms, or to the inside of 
vessels used for keeping oil and fats. 
Stain for Laboratory Tables.f — Herr J. Wortmann recommends 
the following stain for microscopical and laboratory tables. Two solu- 
tions are rubbed into the wood alternately. The first solution is com- 
posed of copper sulphate 100 grm., chlorate of potash 50 grm., water 
615 grm. ; the second, of anilin hydrochlorate 100 grm., chloride of 
ammonium 40 grm., water 615 grm. Each of these solutions is to be 
rubbed in alternately, and the object allowed to dry before using the 
next. The procedure is to be repeated three times. If the surface do 
not turn out black all over, but is smeary, it should be washed with 
lukewarm water, and, after having been allowed to dry, treated to a re- 
petition of the process. 
Two other solutions for the same purpose are also given. Solution 
1 is made of 67 grm. of sodium chlorate, 67 grm. of copper chloride, 
1 litre of water. Solution 2 is composed of 150 grm. of hydrochlorate 
of anilin and 1 litre of water. The solutions are used in the same way 
as the first. 
* Pharm. Era. See Zeitschr. f. ang. Mikr., ii. (1896) p. 153. 
t Bot. Ztg., liv. (1896) pp. 325-7. 
