240 Dr. blagden’s Dijlory of 
the fined configurations of halts. In like manner, with regard 
to quickfilver, Profeflor braun himfelf obferved, that when- 
ever it had congealed but imperfectly, and the fluid part was 
poured off, the folid furface which came in view was extremely 
rough, as if compofed of many imall globules. One of Mr. 
hutckins* s late obfervations exceedingly illustrates this matter; 
for he remarks, that when the fluid mercury was decanted oft, 
in his tenth experiment, “ the internal furface of the frozen 
“ quickfilver (hewed very uneven, with many radii going acrofs, , 
“ l'ome of which had heads refembling pins.’' Now in Pro- 
feflbr blumenbach’s experiment, the quickfllver lying loofe, 
except the flat fide that touched the glafs, could cryflallize 
without impediment, and hence aflhmed a rough, and con- 
icquently a dead-white furface ; whereas in thofe made by Mr. 
braun, with tubes and thermometers, the metal being io 
much confined by the finooth glafs, its furface was rendered of 
a high polifn, not diftinguifhable in point of fplendor from 
that of fluid mercury. Perhaps alfo, M. blumenbach’s quick- 
lilver might have been made to look duller by fome dirt or 
moifture collected upon it from the fal ammoniac and inow. 
§ 3. In the notification of Profefifor braun’s experiments by 
the French Academy of Sciences, a fort of requefl is infer ted, 
that proper perfons might he fent by the Ruffians into Siberia, 
and by the Englifh to Hudfon’s Bay, for the purpofe of re- 
peating them with every advantage of natural cold. I do not 
find that the Ruffians have taken any notice of this, and indeed 
with regard to them it would be almofi: fuperfluous, as fcarcely 
a winter pafles at Peteriburg in which the weather is not fevere 
enough for the ready congelation of mercury by artificial 
means. Butin this country, the Royal Society, ever attentive 
to 
