53 POWDERED DRUGS 



water-bath. Or copper sulphate may be burned until all the water of crystalliza- 

 tion is driven off and a white powder results; then the commercial alcohol maybe 

 poured over this, and the white powder will become blue again from the water 

 absorbed from the alcohol. The alcohol should then be filtered off and kept 

 tightly corked from the air. 



(l) Used in a series of different strengths (from lower to higher) for hardening 

 plant tissue. (2) When sections of plant tissues containing potassium nitrate, 

 dulcite, asparagin, or pipeline are treated under the cover-glass with strong alco- 

 hol, which is then allowed to evaporate, the substances enumerated will crystallize 

 out in their characteristic forms. (3) When pieces of plants containing inulin 

 have lain for some time in 50 or 70 per cent, alcohol, the inulin is precipitated in 

 the form of sphaerocrystals. (4) Seventy per cent, alcohol is used for preserving 

 plant tissues indefinitely, but to avoid shrinkage and disintegration of the pro- 

 toplasts in the case of very delicate or meristematic tissues the material should 

 first have been fixed and brought, by slow degree, to the 70 per cent, alcohol, as 

 elsewhere described. Material which has been preserved for a long time in 70 

 per cent, or stronger alcohol is apt to be quite brittle; when desired, the brittleness 

 may be removed by placing the material for an hour or so in water and then back 

 into the grade of alcohol from which it was taken. Alcohol is used in the prepara- 

 tion of various stains and reagents. The details of its use will be given under the 

 various formulae where it occurs. 



Alum Carmine. A 4 per cent, aqueous solution of ammonia alum is boiled 

 twenty minutes with i per cent, of powdered carmine. Filter after it cools. (Lee). 



Stain from water twelve to twenty-four hours and wash in water. No acid 

 alcohol is needed, since the solution does not overstain. 



Alum Cochineal. 



Powdered cochineal 50 g. 



Alum 5 g. 



Distilled water 500 mils. 



Dissolve the alum in water, add the cochineal, and boil; evaporate down to 

 two-thirds of the original volume, and filter. Add a few drops of carbolic acid 

 to prevent mold. (Stirling.). 



Stain as with alum carmine. 



Ammonium Molybdate. A concentrated solution of ammonium molybdate is 

 made in a saturated solution of ammonium chloride. When sections containing 

 tannins are treated with this, a yellow precipitate is usually produced. 



Ammonium Vanadate. This is used as a test for solanin. The sections are 

 treated with a solution prepared by dissolving i part of ammonium vanadate in 1 ,000 

 parts of a mixture of 98 parts of concentrated sulphuric acid and 36 parts of water. 

 If 4 solanin is present, a yellow color appears, which merges into orange, then dif- 

 ferent shades of red, and finally into violet, and then all color disappears. 



Aniline Oil. Excellent for dehydrating sections, since it will dissolve about 

 4 per cent, of water and may be kept dehydrated by a small piece of solid KOH 

 which isjinsoluble in it. The sections may be transferred from the aniline imme- 

 diately into Canada balsam. 



Aniline Sulphate. Make a saturated aqueous solution. As a test for ligni- 

 fied membranes mount the sections in the solution and add a drop of sulphuric 

 acid, and a yellow color is given to the lignified membranes. 



Balsam. Canada balsam dissolved in xylol is, on the whole, the best medium 

 for making permanent mounts of sections under a cover-glass. Balsam in xylol 

 can be obtained ready prepared of the dealers. 



