REAUMUR 247 



give a first sketch of metallic crystallography. The 

 manufacture of porcelain also interested him ; he sent to 

 China for the materials, and busied himself in searching 

 for similar minerals in France. His memoirs on this 

 subject date from 1727 to 1729 ; his attempts were not 

 entirely successful, but Darcet, and especially Macquer, 

 following the indications given by him, were more 

 fortunate, and succeeded in discovering the fine hard 

 porcelain which we now employ for so many purposes. 

 Reaumur also devised the hard white glass, still known 

 as Eeaumur's porcelain, of which he published an account 

 in 1739. We owe to him the first attempts made to 

 introduce into France the artificial incubation of eggs, 

 practised from time immemorial in Egypt. He showed 

 how to preserve eggs by smearing them with fat, how 

 to hinder the evaporation of spirituous liquors by 

 mercury, and suggested many other processes of greater 

 or less practical utility. He improved the hanging of 

 carriage bodies and the fitting of axles. In 1711 he 

 rediscovered a mollusk which yields a dye answering to 

 the purple of the ancients. He sought to turn to account 

 the silk of spiders,^ and it is a singular fact that his 

 memoir on spiders' silk, dated 1710, was translated into 

 the Manchu language at the request of the Emperor 

 of China, who wished to read in his own language a 

 paper whose title had moved his curiosity. In physics 

 K^aumur is best known by his thermometer, which he 

 brought out in 1731. The freezing and boiling-points 

 of water are taken as fixed points, and the interval 

 divided into 80 degrees, that number being chosen on 

 account of the accidental circumstance that the alcohol 

 which he used dilated Y^hj ^^ ^^^ ^"^^ [^" being brought 

 from the freezing-point to the boiling-point of water] ; 



[^ Spiders' silk proved to be tx>o fino and therefore too oi^etly.] 



