<wiih the Serum or ivaiery Part of the Blood. ^41 



tainly have been more rapid if artifts had been fooner made 

 acquainted with the new chemiftry. This aflertion is proved 

 by the prefent difcovery. 



The neceflity of painting furfaces of different kinds, their 

 various fituations, and the complex circumftances which at- 

 tend the application of colours, have given rife to the differ- 

 ent kinds of painting which are known ; fuch as painting in 

 frefco, painting in fize, oil-painting, painting with milk, 

 painting on porcelain, painting with wax, painting on glafs, 

 &c. 



The journey of the king of Spain to Barcelona, and the 

 preparation of the edifices deftined for the ufe of their ma- 

 jefties, afforded me an opportunity of folviug a new problem 

 in regard to this art. It was neceffary to difcover fome kind 

 of painting of the common colour of ftone which might be 

 able to refift rain, which fliould be unalterable in the fun, 

 eafy to be applied on wood, and which fhould dry foon and 

 exhale no bad odour ; in a word, a painting equally durable 

 with that in fize, and which (liould have the property of being 

 able to withftand the inclemency of the weather. The folu- 

 bility of gelatin in water, the bad fmell of oil, the weak ad- 

 hefion of milk of lime to wood, and its ready alteration by 

 heat, made me fenfible that it would be impoflible to have 

 recourfe to any of the known vehicles for fecuring the co- 

 louring matters. After fome examination I found that al- 

 bumen * was the only fubftance which could anfwer the re- 

 quired conditions, on account of its infolubility in water, 

 and the confiftence it acquires by combining with calcareous 

 earths. This fubftance, prepared by the vital power in the 

 animal organs, is found almoft pure in the white of an egg 

 or albumen, and is found in combination in different animal 

 fubltaiices. But the great vifcidity oF the white of an egg, 

 the clots which are formed bv its combination with lime, and 

 particularly its dearnefs, made me give up all idea of employ- 

 ing it for painting a whole edifice. 



I then conceived that the ferum of blood, the principal 

 part of which confifts of albumen, would be attended with 

 all the advantages of white of egg for the ])ropofed end, with- 

 out having any of its inconveniences. Chemical analyfis of 

 animal lubllances, indeed, lliows that the ferum of blood, 

 commonly called the water of the blood, or, improperly, the 

 lymph of the blood, is a kind of animal mucilage compofed 

 of albuminous or gelatinous fubllanccs in different propor- 



"• This paintihg was mncli wanted for the bridge which joins the botri 

 <if la Douani; t(j ihc putace of trie captain- general, as no other kind could 

 ijt <mployc<l foi fear of iniuiin^; tli<- «iutcn's health. 



Vol. XV. No. 59. K tlons, 



