132 PHILOSOPHY OF ZOOLOGY. 



Many of the parts of animals, which can be dried with- 

 out losing their form, as the skins of many quadrupeds and 

 birds, are afterwards subject to be attacked by insects, and 



" As much of the fleshy parts should be taken from bones intended for pre- 

 paration, as can conveniently be done ; but it is not necessary they should be 

 separated from each other, more than is required for the convenience of 

 placing them in a vessel for the purpose of maceration, as in this process 

 it will readily take place. The bones are to be laid in clean water, of such 

 a depth as entirely to cover them, which water should be changed every day 

 for about a week, or as long as it becomes discoloured with blood ; then permit 

 them to remain without changing, till putrefaction has thoroughly destroyed 

 all the remaining flesh and ligaments ; this will require from three to six 

 months, more or less, according to the season of the year, or temperature of 

 the atmosphere, &c. In the extremities of the large cylindrical bones, holes 

 should be bored about the size of a swan's quill, to give the water access to 

 their cavities, and a free exit to the medullary substance. As by evaporation 

 the water will diminish, there should be more added, from time to time, 

 that none of the bones, or any part of them, may be suffered to remain un- 

 covered, as by exposure they would acquire a disagreeable blackness, and 

 lose one of the greatest ornaments of a skeleton, a fine, white, ivory com- 

 plexion. It will be necessary, in order to preserve the skeleton as clean as 

 possible, especially in London, and other large ckies, where the atmosphere 

 abounds with particles of soot and other impurities, to keep the macerating 

 vessels always closely covered ; as from neglect of this, the water will acquire 

 so much of it, as to blacken the bones. When the putrefaction has destroy- 

 ed the ligaments, &c. the bones are then fit for cleaning ; this is done by 

 means of scraping off the flesh, ligaments and periosteums ; afterwards, they 

 hould be again laid in clean water for a few days, and well washed ; then 

 in lime water, or a solution of pearl-ash (two ounces of pearl-ash to a gallon 

 of water), for about a week, when they may be taken out to dry, first wash- 

 ing them clean from the lime or pearl-ash. In drying bones, they should not 

 be exposed to the rays of the sun, or before a fire, as too great a degree of 

 heat brings the remaining medullary oil into the compact substance of the 

 bones, and gives them a disagreeable oily transparency ; this is the great 

 objection to boiling of bones, for the purpose of making skeletons, as the 

 heat applied in that way has the same effect, unless they are boiled in the 

 solution of pearl-ash, which some are of opinion is one of the most effectual 

 methods of whitening them, by its destroying the oil. Bleaching is, of all 



