258 The Rev. S. Haughton's Notes on Mineralogy. 



2. It is quite as delicate iu its indications as the very best 

 forms of the common areometer, which should consist of at least 

 two instruments, — one for determining the specific gravity of 

 liquids that are denser than water, and the other for those that 

 are lighter than water. 



3. The great advantage of the common areometer consists in 

 the simplicity of its application, no balance being required; the 

 manipulations connected with the use of the instrument here 

 proposed are quite as simple, and at the same time present 

 striking experimental illustrations, suited to the lecture-table, 

 of the relative densities of different liquids. 



4. The scale of comparison in the common areometer is em- 

 pirical, whereas that of the proposed instrument depends directly 

 on a fixed and invariable scientific principle. 



With these advantages, the areometer liei'e proposed may fairly 

 take rank with the ordinary areometer as an instrument capable 

 of determining, within certain limits of error, the specific gravity 

 of different liquids. 



Hastings, February 28, 1859. 



XXXIX. Notes on Miner alog]/. — No. VIII. On the Felspar and 

 Mica of the Granite of Canton. By the Rev. Samuel 

 Haughton, M.A., F.R.S., Fellow of Trinity College, and 

 Professor of Geology in the University of Dublin*. 



THE granite of the neighbourhood of Canton is composed of 

 grey quartz, a light flesh- coloured or creamy- white felspar, 

 in large crystals, and a black glossy mica (crystals f by | inch) 

 imbedded in the felspar and accompanied by quartz. 



The following analyses will show the chemical character of 

 these minerals : — 



Felspar of Canton Granite. 



Per cent. Atoms. 



64-48 1-433 



19-13 0-367^ 



Silica . . . 

 Alumina . . 

 Peroxide of iron 

 Lime 



Magnesia . . 

 Potash . . . 

 Soda . . . 

 Loss by ignition 



;}o-f 



0-56 0007 ''^'^^'^ 



0-45 0016 



12-52 0-266 ^^'^^^ 



3-24 0104 

 016 



100-53 

 From the preceding analysis may be deduced the following 

 relation among the atoms of silica, peroxides, and protoxides : — 

 * Communicated by the Author. 



