No. III.] APPENDIX. 147 



No.m. 



ON THE FORMATION OF MOULDING TABLETS FOR FRAC- 

 TURES. By AuPEED Smee, Dresser at St. Bartholomew's Hospital. 

 (' London Medical Gazette,' February 9, 1839.) 



The importance of a substance that can be moulded accurately to any 

 part of the body at a moment's notice, must be admitted by every member 

 of the medical profession, yet many difficulties attend the formation of a 

 composition which shall at the period of its application be so yielding and 

 soft that it may take an accurate cast of any part, and when dry shall still 

 retain the form, given it, and become sufficiently hard to resist external 

 impressions, and at the same time shall be tough, elastic, and devoid of 

 brittleness and much flexibility; and further difficidties present them- 

 selves, where the capability of its being quickly dried is required. The 

 advantage of lightness and cheapness is also a great desideratum. 



As I had frequently noticed that the composition of gum-arabic and 

 whiting, when dry, possessed great hardness and toughness, and yet was 

 so free from brittleness that it could scarcely be poimded in a mox'tar, 

 I was determined to ascertain how far it would answer to make tablets 

 which might be used to form extemporaneous splints. 



For this purpose a piece of coarse sheeting was copiously brushed 

 over on one surface with a thick solution of gum, after which it was 

 covered with a composition made by rubbing whiting with mucilage, con- 

 tinually adding the powder uutU the whole was of the consistence of a 

 thick paste; a second piece of sheeting was now rubbed over on one 

 side with the solution of gum, and the moistened side applied upon the 

 composition with which the piece of sheeting had been covered, and we 

 thus had two thicknesses of sheeting, with an intervening layer of the 

 composition of mucilage and whiting, the thickness of which may be 

 increased or diminished as strength or lightness is desired. The whole 

 was then dried, and formed a tablet about the thickness of slight 

 pasteboard. 



This experiment succeeded beyond my most sanguine expectations; 

 for whilst the tablet remained dry it wiis exceedingly hard, and, when 

 sponged over with a little warm water, became so yielding that, by mould- 

 ing it with the fingers, a cast could be taken of any part of the body. The 

 hand and knuckles were defined with great accuracy, and I succeeded by a 

 little management in taking a cast of the greater part of the face. It is 

 sometimes advisable not to allow the substance to dry upon the part on 

 which it is moulded ; but after the depressions and elevations have been 

 traced with the fingers, it should be carefully removed and partially dried 

 before the fire, and as soon as the texture is sufficiently dry to retain its 

 shape it may be placed near a stove, or even on the hob of a grate, without 

 fear of corrugating or becoming otherwise deformed. In most cases, 

 however, this drying is quite unnecessary, it being requisite only to 

 envelope the moist tablet with a bandage. A cast thus taken is extremely 

 hard and tenacious, so that when not much thicker than a wafer, it may be 

 struck violently and repeatedly against any hard substance and not be 

 destroyed. It possesses but slight flexibUity, and after being bent returns 



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