Description of an Apparatus for Evaporating Fluids, S^c. 279 



We pour into a flat-bottomed vessel of glass or porcelain, 

 after it is placed in a horizontal position, sulphuric acid, un- 

 til it filled it about one-third of its height, and then place 

 in it several small wine-glasses, and on these, as supports, the 

 vessels with the solution to be evaporated. This arrangement 

 is represented in Plate III. Fig. 4. In order to save room, the 

 supports or wine-glasses should be of different heights, and the 

 vessels of different sizes. I use, in preference, for evaporation, 

 small glass vessels, which are provided with a knob on the bot- 

 tom. In this way they stand more securely, and we can, after 

 a part of the salt is crystallized, pour out part of the solution, 

 and allow crystallization to take place in another part. In order 

 to effect this, we give the vessel an oblique position, by placing 

 the knob on the edge of the support, as represented in Plate 

 III. Fig. 5. ; we can also place the vessel on a larger support 

 or wine-glass, as is represented at u. Fig. 5. Plate III., if the 

 fluid is to be taken from another vessel. If the salt deliquesces 

 in the air, this mode of separating the mother liquor from the 

 crystals is very advantageous. But otherwise it is convenient 

 to place the vessel in the way described, because thereby the 

 mother liquor is quickly and certainly separated ; in salts that 

 do not deliquesce, we rather place the whole in the open air. 



I have found, besides the advantages already mentioned of 

 this form of evaporating vessels, that those in which the bot- 

 tom is flat in the middle, and rounded on the sides, as repre- 

 sented in the figures g g, are the most proper for the formation of 

 crystals, and the most convenient for removing the crystals 

 without injury ; the common semi-globular dishes are by no 

 means so advantageous when the salt is disposed to shoot into 

 long four-sided prismatic crystals or needles ; the crystallization 

 takes place most freely in a vessel with an entirely flat bottom, 

 as d in Figs. 4. and 5. Plate III. 



Another, and probably more convenient, arrangement is the 

 following : We procure a vessel of glass or porcelain, with a 

 flat bottom, and nearly perpendicular sides, and a tubulated 

 bell-glass, having a simple rim, and of such dimensions that it 

 can stand undisturl)ed in the vessel, and when sunk in the sul- 

 phuric acid, atmospheric air will at same time be excluded. 

 Fig. 5. Plate III. represents this apparatus. The opening of 



