J. P. Cooke, Jr., on determining amount, etc. 347 
} only complete register, that of Lieut, Gilliss, in my possession, 
} Ihave not been able to connect the views here presented with 
} the indications of the barometer. This was hardly to be hoped 
for, from a single register, at one locality. 
ndian Summer prevails over a large extent of territory, and 
its laws must be evolved by the discussion of many registers 
kept at places distributed over the whole territory. Smokiness 
is rarely recorded by observers among the phases of the sk 
| and hence previous registers throw little light upon the subject. - 
_ Should the attention of observers, hereafter, be directed to this 
phase, the mass of observations thus obtained may show whether 
the phenomena are simultaneous or consecutive over a large ex- 
tent of country ; whether the barometer rises or falls, &c.; and 
may elicit some law favorable or unfavorable-to the views above 
Suggested ; but which will remove the mystery, which has so 
long hung around the subject of Indian Summer. 
Penfield, Ga., August, 1867. , 
Arr. XXXVI—A method of determining the amount of Protoxyd 
of Iron in Silicates not soluble in the ordinary mineral acids ; by 
Jostan P, Cooks, Jr. 
— : 
less er aes in a mixture of sulphuric and hydro- 
Sahai 
Lo 
This difficulty however may be completely overcome 
