1822.] peculiar Crystals of Sulphate of Potash. 343 
1 to 5, corresponds with M on d, fig. 7, whence he inferred that 
fiz. 7 is a macled crystal consisting of the sections of several 
crystals so united, that M on M or M is precisely 120°, and hence 
it became apparent why these crystals should cleave parallel to 
those planes and to T, or, which is the same thing, to the planes 
of a six-sided prism. The measurement of M on s, fig. 7, since 
taken, confirms the opinion that these crystals are in reality the 
macles already described ; and their structure will immediately 
be perceived on comparing the planes M ds T with the same 
planes of figs. 3 and 6. 
Figures 1 to 6. 
MPAbCMAgsA fe ust h nay esp chatenatone ca sa'aid alec ster SOP ot OF 
POH IM OE Ts cone Wyse nee’ its fe 90 0O 
BEGG OR | Sa Hadcalesd. Ace akon Be 146 30 
VL GIN SE vice, Dah « Deiat siete ote iO s teal AiinO 
WE GA wisn brace deo coharnwe ema dua SaSOuLO 
ity OR Fi. Maa tah « cew «< Mies kan ELoOde, O 
OER SRP re open aide seca acer ar aa orca . 143 «10 
BRON ~ AdaeOd ae dl Me wa edarcte, 6:6 ah, tee cal 
ROM Mes ctin ms cima nibiieaateee I3e: 20 
ONE Orr Ce eee SONY BOLO ONE 
1s te cy Mare ahh Se aed ai baad ll4 0 
Ge ere OE ep ene Se ee dy ides 
pean: CH) Voie Sot ot speed 
rvcrittic eige x"... teams «a s(s.s « "190 ot 
Mon 7s ES, ts AME a alde wees te, OU 
WEOMNHD Stee 2 ane scat eee at Le. OU 
eres te, oe Oe eae testa leo, oO 
bec ed At pat. . eagh re elie a | famine 
ro Ce) ee a AR «iat iawe tou... 8 
Figure 7. 
1) es LY, OPES A a ee MOO 0 
IME Oni or d/o. Poul, Preis IMS SO 
beans 43,0) Ol HOI Se ee Tape Gg 
Wiioaio!S Jee. Zo, pee TO" -O 
Whang, ou eee too YO 
ArricLe VI. 
Extract from a Memoir on the Composition of the Alkaline 
Sulphurets. By M. Berzelius. 
(Continued from p. 288.) 
I, THEREFORE, mixed some subcarbonate of potash with a 
great excess of sulphur, and heated the mixture until the sul- 
