Von Bichthqfen on the Porcelain rock of China. 179 



with its tubes m and n is sunk bj C in tlic inner v.'ssrl of ila' 

 instrument, and finally the tubes m and // arc phuod on tlhM'or- 

 nsjHiudino- glass tubes of the cooling ai»]Kir;itus. If now. aftt^r 



nnL-coXl!emri^d^ltmia^^^^ 



diu-mg X C c'viimior. ^^'The 'iornuition'ol^lu. lathT in thr ap- 



sonts not uninteresting peculiarities. Tlu' tiiiiiicratun' ol ihf 

 l»>'rf(>cilv airless water in the outer vessel />, lig. 1. sink> i^radu- 

 ally, without freezing taking place, until far below o (\. winh 

 the vessel covers itself externally with an ice crust irom thr 

 precipitated moisture of the atmosphere; even strong agitation 

 is insufficient to put a stop to this abnormal fluidity. Wlieii 

 the temperature has finally sunk very low, a sudden lormatn.n 

 takes place, which propagates itself in a few seconds 



the water mass from ;< 

 ntrary unfrozen. Now 

 beirms, under continued cooling, the first formation of the ice 

 cylinder, which is allowed to increase until its walls have 

 attained a thickness of about 6 to 10°^'". That part of the ver\- 

 re-ularlv formed ice crust which lies below /^ appears perfeetlv 

 :niio]|,lious, clear and transparent as the purest crystal glass ; 

 tlie poi-tion above n reaching to A appears turbid and of a tex- 

 ture not dissimilar to the confused coarse-fibrous, after the 

 mstrument has stood several days ready for use at 0^ C. m the 

 ^now this coarse-fibrous texture changes entirely. The ice 

 mass between A and // consists now of small rounded transpa- 

 rent grains of spherical habitus; if, after long use, the instru- 

 nuMit be exposed to the temperature of the room, the individual 

 ■'Spheres melt off on their surfaces, detach themselves thereby 

 ii'oni the adjacent mass, and rise in the fluid ; they then appear 

 at times connected with one another like the cells of yeast 



[To be continued.] 



Art. XXVIL— Oji the Porcelain rock of China; by Baron VON 

 RiCHTHOFEN.— From a letter to Prof. J. D. Whitney, dated 

 Shanghai, Nov. 17, 1869. 



I HAVE recently made a verv pleasant trip of six weeks, going 

 ^ip the Yang-tse to Kinkiang, then into Poyang lake. 1 visited 

 some places" on its eastern affluents, among them the famous 

 King-te-chin, where the Chinese have made nearly all their 

 porcelain for almost three thousand years. I examined the 

 places from which thev take the material, crossed over into 



