194 BROCK PlirNTIXG,. &G. 



The whale report of M. Darcet may be read in the Bulletm 

 de la Soc'utt d' Encouragement, No. <20, Feb. 180(). It is 

 not a simple process, but an art described in a clear and sim- 

 ple manner, with all its circumstances, such as we could wish 

 the description of every art to be given. 

 Principal The two principal" points are the preparation of the moulds, 



attended to. ^"^^ ^^^ metal intended for stamps. Though good sfam,ps may 

 be obtained by letting a perfectly dry plastc^r mould fall on the 

 fusible compound of bismuth, tin, and lead,. M. Darcet ha^ 

 thought that, if he could impart more sohdity to the plaster, 

 and fill up the pores that form bubbles or diminish the polish 

 of the stamp, he should improve the art very much. After 

 having tried several means he has preferred Flanders glue. 

 Method of ma- " Three ounces and half avoirdupois weight of fine Flanders 

 ter mould^. S^"^ ^"^^ ^^ bc steeped, and then dissolved by heat in four pints 

 They are and half of water, 'the. solution being strained through a piece 



steeped in r r ^■ • • ,1 T •,, • . , ••• , 



weak hot glue.. °^ "'^^ uxien or a sieve, is to be heated till it is near boiling, and 



the plaster moulds, previously dried and slightly heated, arQ 



then to be immersed in it. The air they contain expands and 



escapes, while the water, taking its place, carries with it into 



the interior parts of the mould the glue which it held in a state 



of considerable attenuation. As soon as the air ceases to be 



disengaged, the plaster mould is to be taken out and shaken, 



and the operator must blow strongly on its engraved surface, 



that pellicles of glue may not be formed in cooling, which 



would impair the delicacy of the work." 



The mou'Ws thus saturated should be dried slowly ; toward 



tlie end, however, the temperature may be raised as high as 



50° or 60° of the centigrade thermometer (112° or 1 40° Faibt.) 



The moulds The moulds thus saturated with glue must not be used except 

 must be kept , . , , , . „ , . . 



dry, and used ^^"^J^ very dry ; and as they attract the moistnre of the air, m 



dry and cold, consequence of the glue contained in them, they must be kept 

 ill a dry place, or heated before they are used, taking care 

 to let them grow cold before the metal is stamped with them. 



Davcet's fusi- ^^ iq i]^q metallic compound, it was invented by JNl. Darcet. 

 senior. That worthy man, who found no pleasure in his dis- 

 coveries without rendering them public and useful, made this 

 known in the years 1/73 and 1777, by means of the Journal 

 fic Mcdcdne and the Journal de Fhysique. It has since beeq 



employed 



>)k' metal, 



