APPLICATION or PLATIKA 6N PORCELAIT*. 28^!| 



Platina in its qualities ranks with gold, and by its whitenefs Platina imitates 

 fiipplies the place of lilver^ without labouring under its de- ^^^^^^ "^J^^'Jf^^^.** 

 flscls. It not only covers the ground well by its denfity, which hav ng its de- ' 

 even furpafles that of gold ; but like this it refifts all the alter- ^^^^^' 

 nations of the atmofphere, and is not any way tarniQied by ful- 

 phurous effluvia. 



The procefs for applying it is very firaple. Platina is dif-Procefsof ap. 

 folved in nitro-muriatic acid, and precipitated by a folution of ^'^'"* ^^ 

 muriate of ammonia. The red cryftalline precipitate formed 

 is to be dried, reduced to a fine powder, and made (lightly red 

 hot in a glafs retort. The muriate of ammonia, which had 

 precipitated in combination with the platina, fublimes ; and 

 the metal remains at the bottom of the retort, in the form oF 

 a Tight, gray powder. This powder being mixed with a fmall 

 proportion of flux, as is done with gold, and ground with oil 

 of Ipike, is to be applied to the porcelain, put into the fur- 

 nace, and afterwards burn iflied. 



Platina applied on porcelain in this manner, is of a filver it refemb!e« 

 white, (lightly tending to the gray of (leel. By alloying: this ^'^='" ^^'•^^ a 



. 1 • lo- . .• •:. ij ra- . n a ,> flight ftee.l tinge. 



metalm ditterent proportions with gold, different (liades ofooldin differ- 



this colour are obtained. Platina admits a contiderable quan- ^"t piopordons 



tity of gold, before its colour undergoes any perceptible change but does^n t^ ^ ' 



to yellovy. For example, if one part of platina be alloyed render it per- 



wilh four parts of gold, the prefence of the latter cannot be "P'^'j''^ ^^''^^f 

 ^ . t . unlefa 4 parts 



perceived, and the colour Icarcelj ditFers from that of pure of gold b.. added 

 platina. The colour of the gold does not predominate, uniefs ^^ ' ^^ platina ; 



f . . . ,• f • L. . 2"<^ t^^t goid co- 



lt be in the proportion or eight to one. lour does not 



The alloys of platina with filver give only a dull metal. predominate. 



Betide this method of applying platina to porcelain, it may "h" VrJp >rtion 



be laid on in the (late of folution. In this way its colour, luftre, of 8 to i. 



and appearance, are very different. If the nitro-muriatic fo- yg,!:'^"|JJ^"^ ?' 



lution of platina be evaporated to a certain confidence, and alloy. 



laid on the porcelain feveral times, the metal penetrates into ,V^'^'"^'"^>^ 



its fubftance, which, after it comes out of the furnace, exhi- plied in foJu^/', 



bits a metallic mirror of the colouf and brilliancy of polithed ^'"" » 



r, , and this, if fe- 



*^®®^* ▼eral coats be 



laid on, pene- 

 trares the fub- 

 ftance, and pro- 

 duces a mirror 

 refambling 

 poliihed fteel. 



• . X. Ahpaa 



