364 REAGENTS AND THEIR PREPARATION [Ch. X 



quickly, in from one to three days. (Proc. Amer. Micr. Soc, Vol. 

 XII (1890), pp. 120-122.) 



§ 587. Picro-fuchsin. — 10 cc. of a 1 % aqueous solution of acid 

 fuchsin; 75 cc. of a saturated aqueous solution of picric acid. Stain 

 deeply with hematoxylin first; then use the picro-fuchsin. Wash 

 off the picro-fuchsin with distilled water. Mount in non-neutralized 

 balsam, or better in acid balsam (balsam 50 cc, glacial acetic acid 5 

 drops). If the white connective tissue is not red enough, increase 

 the amount of acid fuchsin. 



§ 588. Shellac cement. — Shellac cement for sealing preparations 

 and for making shallow cells is prepared by adding scale or bleached 

 shellac to 95 % alcohol. The bottle should be filled about half full of 

 dry shellac ; then enough 95 % alcohol added to fill the bottle nearly 

 full. The bottle is shaken occasionally and then allowed to stand 

 until a clear stratum of liquid appears on the top. This clear, super- 

 natant liquid is then filtered through filter paper or absorbent cotton, 

 using a paper funnel (§ 545), into an open dish or a wide mouth bottle. 

 To every 100 cc. of filtered shellac 2 cc. of castor oil may be added to 

 render it less brittle. The filtered shellac will be too thin, and must 

 be allowed to evaporate till it is of the consistency of thin syrup. It 

 is then put into a capped bottle, and for use into a small spirit lamp 

 (fig. 194). In case the cement gets too thick add a small amount of 

 95% alcohol or some thin shellac. The solution of shellac almost 

 always remains muddy, and in most cases it takes a long time for 

 the rlocculent substance to settle. One can quickly obtain a clear 

 solution as follows: when the shellac has had time to thoroughly 

 dissolve, i.e., in a week or two in a warm place, or in less time if the 

 bottle is frequently shaken, a part of the dissolved shellac is poured 

 into a bottle and about one-fourth as much gasoline added and the 

 two well shaken. After twenty-four hours or so the flocculent, un- 

 dissolved substance will separate from the shellac solution and rise 

 with the gasoline to the top. The clear solution may then be siphoned 

 off or drawn off from the bottom if one has an aspirating bottle. (R. 

 Hitchcock, Amer. Monthly Micr. Jour., July, 1884, p. 131.) 



If one desires to color the shellac, the addition of a strong alcoholic 

 solution of some of the coal tar colors is good, but is liable to dissolve 



