Anatomical Prep aval ions. 299 



mediate vessel as long as conveniency may require. The solu- 

 tion in which they are fiualiy to be kept should be a very little 

 below sr.turation. Evaporation is much less liable to happen 

 than if spirit is employed ; yet should it occur, from any acci- 

 dent, crvstallization would resuir, unless this precaution were 

 adopted, i have added about half an ounce of very clear water 

 to a quart of the saturated solution. 



" All kinds of animal structure do not exhibit the same rela- 

 tive gravity when saturated with the solution ; some will float 

 whilst otiiers sink. In the final operation of preservation, the 

 latter undergo the same treatment as is adopted with spirit, viz., 

 by supporting them with delicate threads of silk ; but the former 

 require sortie body to give them an increase of gravity. 



" In almost all preparations it is requisite to keep certain parts 

 separated by means of quill, bristle, or other insoluble substance ; 

 instead of these, I use delicate pieces of glass, which may be ob- 

 tained from the glass-blowers of every degree of fineness. These 

 answer fully; they look neater than any thing else; can be ap- 

 plied with great facility; render sufficient weight, and are of very 

 little cost; for a few pence I purchased enough to last some years. 

 In the specimen of ulcerated intestine, the glasses applied [as 

 stated in the former letter] were not intended to be permanent; 

 I had not then procured the glass from the manufacturer. Mem- 

 branous parts it is customary to spread on talc, as two of the 

 specimens are applied now with you. I think, however, by sus- 

 pending a fine cvlinder of glass at the bottom, the part retains a 

 more natural appearance ; and, therefore, of late, I have entirely 

 relinquished the talc. 



" When the specimens are put into a solution of proper 

 strength, and perfectly transparent, and the parts properly sepa- 

 rated, to exhibit the different objects it is designed to show, the 

 next point of importance is to close the bottles with accuracy 

 and neatness. 



" For the reasons already stated, glass, with a medium of 

 resin, was chosen. I make the rim of the bottle perfectly dry> 

 and spread on it some resin, with a commou spatula. The glass 

 (previously fitted) is then applied, and by holding the warm spa- 

 tula pretty close to it, the resin softens, and the top is fixed with 

 the utmost accuracy. I have thought it best to conduct this 

 process in a moderately warm room, and the glass should be ra- 

 ther less than the circumference of the rim, or on lifting the bot- 

 tles by the top, as is very generally done, the glass might be 

 raised. With small bottles it is sufficient to make the resiji 

 smooth, and then varnish it ; but ou bottles of a larger size, ad- 

 ditional security is obtained by attaching a slip of bladder around 

 the edge, by mean* of glue, 



Z 2 " When 



