On melanophlogite. — Streng. 
327 
Ontabian 
System. 
Keewatin Group. 
(Possibly Huronian.) 
Upper Series. 
Van Hise's Break. 
Lower Series. 
Unconformity? 
ARCH- 
AEAN. 
Coutchiching Group. 
Ibrtjptive Un- 
conformity. 
Latjeentian 
System. 
Note— While writing on tins subject it may be well for me to state that the late 
Prof. Alexander Winchell was in error in supposing-, as appears on page 218 of 
his recent paper, " American opinion on the older rocks," that I ever regarded 
the Animikie and Keweenawan as part of the Archaean. I have never entertained 
that idea for a moment and have been entirely misunderstood on this point by 
nay late lamented friend and fellow worker in lake Superior geology. A. C L. 
ON MELANOPHLOGITE.* 
By A. Streng, Giessen. 
In the twenty-seventh volume of the Oberhess Ges t fur Nat. u. 
Heilkunde, p. 123, I have offered some observations on melano- 
phlogite in which I announced that the material at my command 
contained no S0 3 but sulphur in a different combination. Re- 
cently different works b}^ Pisani and especially by G-. Friedel 
( Sohn ) in which a content of S0 3 is announced as certain, aroused 
in me some doubt as to the correctness of rny results, and es- 
pecially it appeared to me as possible that my specimen may not 
have been a true melanophlogite but a pseudomorph of melan- 
ophlogite after quartz or opal. After more extended examination 
I have discovered however that this doubt was not justified ■ for I 
found in the same material in which I had been unable to find any 
S0 3 in solution in HF1, 3.82 per cent of S0 3 in a decomposition 
in NaC0 3 . Nevertheless I repeated my efforts with every con- 
ceivable precaution and variation, to show the presence of SO in 
the fluoric acid solution, but without reaching any other result. 
As it was so well established that my sulphur-bearing melan- 
ophlogite contained no S0 3 , I knew the sulphur present in it was 
in some other combination. 
If now melanophlogite contains, in the indicated absence of a 
*Translatcd from the 28th Bcr. d. Oberh. Ocs. f. Nucur. u. Hellk. 
