120 THE AMEEICAN MONTHLY [May, 



MICROSCOPICAL APPARATUS. 



A Revolving Table. — I. Saw out a circular board iS inches 

 in diameter and ornament the edge if you choose. On the under 

 side, and about 2 inches from the edge, phice 4 castors equidistant, 

 and have the board rest firmly on them. In the centre of the 

 underside bore a hole nearly through the board and insert a piece 

 of brass tube. Stain or paint the board at pleasure. 



II. Cut a piece of thick pasteboard iS inches square and to the 

 centre of it fasten a block 2x2 inches by i inch thickness, letting 

 a brass pin stick up an inch from its centre, liaving it of such size 

 as to work loosely in the tube. 



III. Place the second apparatus on a small stand or table, ad- 

 just the first apparatus over it so that the pin will fit into the tube, 

 revolve the top part upon the pin as a centre guide and upon the 

 castors as lateral supports. If the castors are noisy make a track 

 with felt for them to run on. 



This is the device of Mr. F. S. Morton. 



MICROSCOPICAL MANIPULATION. 



Glycerine, C.^ H- 3 H O, is the hydrate of the trivalent radical 

 glyceryl. It is a sweet syrupy liquid, obtained bj' the decompo- 

 sition of fats and oils, principally as a by-product in the manufac- 

 ture of candles and soaps. The fatty acids are used to make 

 candles and soaps, when combined with soda or potash. Pure 

 glycerine is colorless and odorless, freely miscible with water and 

 alcohol in all proportions ; but with oils it only emulsifies, and 

 does not perfectly blend. It is a solvent of many alkaloids and 

 their salts, as well as resins. The purest is prepared by distilla- 

 tion ; although not volatile without decomposition, yet it passes 

 over undecomposed in the vapor of water, and may be concen- 

 trated by careful evaporation. This mode of preparing it was 

 patented by Price's Candle Company, but now much distilled 

 glycerine is imported from Germany. Glycerines of inferior 

 quality have a disagreeable smell, and are sometimes colored. 

 Good glycerine should not be colored after being subjected for 

 two hours to the action of an added solution of the nitrate of silver. 

 — Cole. 



Glycerine Jelly. — Take of gelatine, 300 grains; distilled 

 water, 6 ounces ; glycerine, 6 ounces ; rect. spirit, 6 drams ; white 

 of egg, 6 drams ; salicylic acid, 12 grains. Let the gelatine soak 

 thoroughly in the water, then dissolve in a water-bath : add the 

 spirit, and mix well. When cool, but still fluid, add the white of 

 egg, mix, and heat to boiling point to completely coagulate the 

 albumen ; add the glycerine with the salicylic acid in it by the 



