54 



THE AMERICAN MONTHLY [February, 



ervoir of this size will hold, without crowding, thirty prepara- 

 tions on l^-inch covers. It is desirable to have a reservoir for each 

 of the liquids used. The cheapness with which they can be made 

 does not render this objectionable. 



The construction consists in procuring the desired number ot 

 " double dishes," a few feet of glass rod, and an ounce or two ot 

 liquid glass (silicate of soda) or a few feet of fine copper wire. 

 The glass rod is easily broken, by the aid of a file, into pieces ol 

 the required length, which are fastened in their respective places 

 by means of a few drops of the liquid glass. In order to raise 

 them from the bottom of the dish a ring composed of the liquid 



Fig. I — Cover-glasses in position. Fig. 2 — Cross-section. | Fig. 3 — Mat of 



glass rods. 



glass is built up around the edge, upon which the ends ofthe rods 

 can rest and upon which they are fastened. As the silicate ot 

 soda is soluble in water and dilute alcohol, it is necessary to 

 dehydrate it after the rods are fixed, so as to render it insoluble. 

 This can be done by heating the reservoir in an oven or hot-air 

 chamber at a temperature of about 98° C. If the reservoir is to 

 be used only for turpentine, absolute alcohol, etc., the drying of 

 the silicate of soda in the air is sufficient. 



Instead of fastening the rods in the dish they can be bound to- 

 gether by means of fine wire, preferably copper, in the form ot 

 mats, which answer every purpose and which can be removed at 

 will if the dish is desired for other purposes. This is easily ac- 

 complished by running the wire around the ends ofthe rods after 

 they have been cut the desired lengths. A shoulder-like projec- 

 tion can be procured on the ends of the rods by heating them 

 until soft and pressing them against a firm surface. These pre- 

 vent the wire from slipping oft', and also raise the rods from the 

 bottom of the dish (Fig. 3). 



With a full set of these reservoirs thirty cover-glasses can be 

 carried from the first to the last liquid quite as quickly as a single 



