1900] MICROSCOPICAL JOURNAL. 309 



tion of eosiD to make the whole strongly red. The glass 

 is now exposed to a strong light, and the liquid rapidly 

 darkens, becoming by direct light almost as black as ink, 

 but when viewed by transmitted light, of a dark port wine 

 color. It is then let stand until all the sediment is gath- 

 ered at the point of the cone, when the supernatant fluid 

 is drawn off, and the glass refilled with distilled water : 

 After settling, the liquid is again drawn off, and another 

 charge of distilled water added to the sediment. This is 

 repeated until the added water no longer shows a trace of 

 color, when, after the subsidence of the solid matter, it is 

 drawn off, to the last drop, strips of bibulous-paper being 

 used to absorb the minute residue. The best for this pur- 

 pose is a linen blotting paper, which has been submitted 

 to a certain amount of pressure, and showing diagonal 

 lines of an eighth of an inch, the effect of which is the 

 prevention of separation of the fibers, and their mixtures 

 with the sedimentary deposit. 



To the moist sediment, a few drops of glycerin (or if 

 the operator is not expert in making glycerin mounts, of 

 warm glycerin jelly) are added to the sediment, stirred in, 

 and the vessel rotated until the sediment is evenly distrib- 

 uted throughout the mass. It is now ready for mounting, 

 and may be treated exactly as any other glycerin or glyc- 

 erin jelly mount, the only precaution necessary being, 

 as we have frequently stated in discussing the perma- 

 nence of glycerin mounts, the use of prepared slips, the 

 cell-walls of which are old and thoroughly dry. The writer 

 prefers for this work a cement made of zinc oxide in a so- 

 lution of damar in chemically pure (the so-called "crys- 

 tallizable") benzol, to which, to avoid brittleness, about 

 one per cent of old gilders' size, and a much smaller quan- 

 tity of castor oil has been added. Such cells reach, very 

 nearly, their limit of shrinkage from desiccation in from 

 eight to ten months, but it is better to give them a year 

 of seasoning. A carefully made glycerin mount, in cells 



