314 Mr. Drach on Observatiofi-Hoursjbr Meteorologists. 



indeed to 2*663, as obtained by experiment, where the iron, 

 manganese and alumina might have lost during ignition a 

 small quantity of sulphuric acid. 



A few small flakes, which were found floating in the water, 

 and which were separated, remain finally to be noticed. These 

 flakes consisted chiefly of oxide of iron with a small propor- 

 tion of organic matter. The oxide of iron upon 16 ozs. 

 amounted to 0*384 gr., which had become separated (as I was 

 assured) from the water in the bottles, and must have existed 

 previously in the form of a proto-carbonate of iron, which 

 would be equivalent to the amount of 0'56175. On adding 

 this to the iron found in solution, 16 troy oz. of the water would 

 contain at its source 0*61255 gr. of proto-carbonate of iron, 

 or in 1000 grs. 0*07975 gr. 



For convenience sake the calculation upon the imperial pint 

 is added. 



In 1 pint = 34*659 cubic inches (at 60° F. spec. grav. 

 1*002618) = 8772*907 grs. 



grs. 



Sulphate of potassa 2*46554 



soda 1*51227 



lime 6*28166 



Iodide of sodium 0*00728 



Bromide of sodium 0*07886 



Chloride of ammonium 9*49939 



sodium 3*82963 



magnesium 3*12017 



Nitrate of soda 2*02154 



Carbonate of magnesia 1*70443 



Proto-carbonate of iron 0*05807 



,.. ... manganese .... 0*01535 



Ammonia (united to organic matter) . . 0*42285 



Alumina 0*02245 



Silica 0*18651 



Total .... 31*22600 

 The whole amount of proto-carbonate of iron in 1 pint at 

 the source = 0*69973 gr. 



XLV. On Observation-Hours convenient to Jmateur Mete- 

 orologists^ and adequate for obtaining Mean Values. By 

 S. M. Drach, Esq., F.R.A.S."^ 



THIS important selection for the furtherance of meteoro- 

 logy by those whose avocations do not permit of conti- 

 nual attention to their instruments, having been expatiated 

 * Communicated by the Author. 



