MODELLINGrCOMPOSITIONS, CEMENTS, ETC. 79 



is an advantage to cover clay models with pasted tissue-paper 

 to prevent cracking. 



For rough or large work, modelling -clay is very well 

 replaced by common fire-clay, or even by the common clays of 

 the fields, some of those known to geologists as lias clays 

 being the most tenacious and useful. 



For insertion within the skins of animals, to assist the model- 

 ling of the head and limbs and so on, clay is, though somewhat 

 heavy, exceedingly useful, and in connection with this it may 

 be as well to point out to Mr. Hornaday,^ who claims to have 

 "discovered its value" in 1880, that the English taxidermists 

 used it for these purposes long before the American, and, if they 

 did not discover it, there is every probability that the foreign 

 {j.e. European) taxidermists used it long ago. 



Of modelling-wax it is only necessary to state that, being 

 rather expensive either to buy or to make, its use is limited to 

 small objects or to the representation of parts. The same 

 may be said of guttapercha ; this latter is, however, by no 

 means a good medium in which to work. 



Modelling-Compositions which in a short time become 

 extremely hard 



Hamilton {Pathology, p. 719) says, " Where a very strong 

 substance is required in constructing a model, gilder's putty 

 may be found useful. It has the following composition : — 



60.— Gilder's Putty 

 Resin . . . . . i lb. 



Glue . . . . . . I „ 



Boiled linseed-oil . . . .2 gills 



Precipitated chalk, a sufficiency. 



"The glue must first be thoroughly soaked in water and melted. 

 The resin is to be dissolved in the boiled linseed-oil, and the 



' Taxidermy and- Zoological Collecting, -p^. 112, 113. 



