54 



THE AMKRIOAN MONTHLY [FoLinaiy 



civoir of tliis size will lu)Kl. w itlioiit crnwiiinjj;, tiiirlN prepara- 

 tions on jf-inch covers. It is tlesirable to have a reservoir l\)icach 

 of the liquiils uscil. The cheapness with which they can he made 

 does not rentier this t)l>iectionahle. 



The construction consists in procurinji^ the desired nimilier ol 

 " tlouble dishes." a tew teet of «j[las-s rotl, and an ounce or two ot 

 liquid ;.^lass ^silicate of soda) or a few leet of line copper wire. 

 The «ilass rod is easilv broken, by tlie aiil of a file, into pieces ol 

 the leijnired length, which are fastened in their respective places 

 bv means of a few tlrops of the li(|uid •jjlass. In order to raise 

 them from the bottom of the ilish a rinj^ composeil of the litjuid 



Fig. I — Cover-gl.isses in position. Fig. 2 — Cross-section. Fig. 3 — Mat of 



glass rods. 



glass is built up around the edge, upon which the ends of the 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 

 dehv(bate it after the rotls are fixed, so as to render it insoluble. 

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

 chamber at a tempcratine 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 tliev can be bound to- 

 gether bv 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 of the 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 ofl'. 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 (piite as quickly as a single 



