ANILINE OIL BERLIN BLUE 287 



Aniline Oil. Excellent for dehydrating sections, since it 

 will dissolve about 4 per cent, of water and may be kept dehy- 

 drated by a small piece of solid KOH which is insoluble in it. 

 The sections may be transferred from the aniline immediately 

 into Canada balsam. 



Aniline Sulphate. Make a saturated aqueous solution. 

 As a test for lignified membranes mount the sections in the solu- 

 tion and add a drop of sulphuric acid, and a yellow color is 

 given to the lignified membranes. 



Or pour sulphuric acid slowly into aniline oil until a pre- 

 cipitate is produced throughout and then add water until the 

 precipitate is dissolved. This will not require the addition of 

 sulphuric acid to the sections. 



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

 the best medium for making permanent mounts of sections 

 under a coverglass. For the method of doing this see page 

 265. Balsam in xylol can be obtained ready prepared of the 

 dealers. 



Barium Chloride. This is sometimes used to distinguish 

 calcium oxalate from calcium sulphate. When barium chlo- 

 ride is run under the coverglass, calcium oxalate, if present, 

 is left unchanged, while a fine granular layer of barium sul- 

 phate comes to incrust any crystals of calcium sulphate. (2) 

 To determine the presence of tartaric acid, barium chloride 

 and antimonic oxide in hydrochloric acid is run under the cover- 

 glass, producing, with tartaric acid rhombic crystals of anti- 

 monium-barium-tartrate, whose obtuse. angles measure 128. 



Benzol. Used in detecting caffeine, thus: Sections are heated 

 on the slide in a drop of distilled water until bubbles arise, 

 then the water is allowed to evaporate, and the residue is dis- 

 solved with a drop of benzol. The benzol is then allowed to 

 evaporate and the caffeine is deposited on the edge of the 

 drop in the form of colorless needle-crystals. 



Berlin Blue. Useful in the study of the growth in thickness 

 of the cell-membranes. In the study of marine algae notably, 

 Caulerpa prolifera it is used in the following manner: A vigorous 



