WITH THE MICROSCOPE. 2O I 



platinum basin or foil may be supported over the lamp upon coarse 

 wire gauze or upon a piece of wire, bent in the form of a triangle, or 

 upon one of the small rings attached to the spirit lamp, pi. XIV, 

 fig. 70. It may be removed from the lamp with the aid of an old 

 pair of forceps. 



286. Apparatus. The chemical apparatus necessary for the 

 microscopical observer is very simple, and the greater number of in- 

 struments have already been referred to. The following are among 

 the most important pieces of apparatus : 



A few conical glasses of different sizes. Apparatus for taking: 

 specific gravities. Test-tubes of various sizes, arranged on a stand, 

 pi. XLV, fig. 282. Spirit-lamps, with various supports, pi. XIV, 

 fig. 70, or, where gas is laid on, the gas-lamp, pi. XI, fig. 49. Glass- 

 funnels and filtering paper, pi. XXII, figs. 139, 147, small porcelain 

 basins, watch-glasses ; a simple water-bath, pi. XIV, fig. 73, or the 

 injecting can, pi. XXIII, fig. 152, may be used, if several evapora- 

 tions are to be conducted at once. A small platinum capsule, a 

 strip of platinum foil, a blow-pipe, pipettes, pi. XXII, fig. 140, and 

 glass stirring rods, with a box of reagents in small bottles, pi. XLV, 

 fig. 279, and test papers, complete the apparatus. All these may be 

 obtained, packed in a box of convenient size, fig. 284. 



287. Microscope for Examining Substances Immersed in Acids 

 and Corrosive Fluids. If preparations which require to be immersed 

 iii strong acid, be examined in the ordinary microscope, the fumes 

 may injure the brass work of the instrument. Considerable incon- 

 venience is also experienced in examining fluids while hot, in conse- 

 quence of the vapour rising and condensing upon the object-glass, 

 and thus rendering the object invisible. 



The ingenious microscope invented some years ago by Dr. Law- 

 rence Smith, obviates these objections. This inverted microscope 

 has been described in p. 183, and is represented in pi. XLIII, fig. 271, 



REAGENTS AND THEIR ACTION. 



The reagents necessary for the microscopist are not very nume- 

 rous. They should be perfectly pure.* Of the greater number only 

 very little is required, as much as may be kept in drachm or two 

 drachm bottles ; but of alcohol, ether, and one or two others, it is 

 necessary to have a half-pint or more. The stock reagents should 

 be kept in stoppered bottles of about the capacity of two ounces. 



288. Distilled Water should alone be employed for dissolving 



' Pure chemicals may be obtained of Mr. Gri-Tin, Long Acre. 



