^xt M^mufa&vyf of Hirn.-^Metallk Suhjlitutt. 



VJI. 



On the Art of covering Wire Cloth with a tr an/parent Varnijh, as a Suhjlitute for Horn ; and on 

 other ObjeSls of public Utility. By JlzXIsRocHON^ of the National Infitute of France, b'f.* 



I 



N the progrefs of the prefent war, the marine flore-houfes of France were totally with- 

 out the efleiitial article of horns for lanthorns. It was impoffible to fubftitute glafs in the 

 place of this article, on account of its brittlenefs, and the obvious danger which might refult 

 from that quality. In this fituation of diftrefs, the agents of the French government con- 

 fultcd Citizen Rochon, and directed him to make every experiment he could think of to dif- 

 cover a proper fubftitute. His attention was firft diredled to a memoir of the celebrated Poivre 

 on the fabrication of lanthorns of horn by the Chinefe. It is known that this induftrious 

 nation prefer horn to glafs on account of its cheapnefs and toughnefs, and that they poflefs 

 the art of welding this fubftance together with fo much delicacy, that they make lanthorns 

 of two feet diameter of aftonifliing tranfparency, and to all appearance of one fingle piece- 

 It is alfo known that the Chinefe ufe the horns of goats and (heep only, which they foften and 

 fplit into lamina: by procefles fuppofed to be unknown in Europe ; or, perhap , by employ- 

 ing a proportion of human labour and patience for that purpofc which the European de- 

 mand might be inadequate to repay. Citizen Rochon, who does not appear to be perfedly ^ 

 aware of the degree of accuracy with which the fame art of fplitting horn is prai^ifed in 

 Europe, propofed, that the horns of beeves fliould be fawed into laminae, and then fcraped 

 and poliflied ; or, to which he gives the preference, that they fhould be laminated in boil- 

 ing water. 



While this aftive philofopher was employed at Breft in eftablilhing a manufadlory for 

 laminating the horns of beeves, which he purpofed to reduce into the ftate of a pafte by 

 means of pure alkali in the digcfler of Papin, it occurred to him, that he might fupply 

 the prefling wants of the navy by another expedient, whichtconfifted in the application of 

 a coating of glue upon wire cloth. 



In this procefs, he at firft tinned the Iron wires of the fieve cloth he made ufe of, but 

 afterwards found it more convenient, in every refpe£l, to give it a flight coating of oil 

 paint to preferve it from ruft. The glue he made ufe of was afforded by boiling the clip- 

 pings of parchment with the air-bladders and membranes of fea-fifh ; materials which he 

 ufed, not from any notion that they were preferable to ifinglafs, but becaufe they were the 

 cheapeft he could procure. He added the juice of garlick and cyder to his compofition, in 

 proportions which, I fuppofe, he did not meafure, but which he found to communicate 

 great tenacity and fomewhat more of tranfparence than it would have poflefTed without 

 them. Into this tranfparent and very pure glue or fize he plunged his wire cloth, Mhich 

 came out with its interftices filled with the compound. It is requifite that the fize (hould 

 pofiefs a determinate heat and confiftence, concerning which, experience alone muft guide 

 the operator. 



• Extrafted from a memoir read to the National Inftitute of France the lift Ventcfe, in the year VI. 

 (March nth, 1798), and infcrted in the Journal de Phyfique for April 179S. The memoir contains various 

 political and economical oblervations more particularly applicable to France, with general obfervations, which I 

 have not thought it neccflary either to tranfcribe or abridge ; neither have I been folicitous to take the very 

 ■wards of my author in the parts I have abftraftcd. N. 



Whea 



