Na Analyses of Books. [Aprit, 
have not yet attempted it; but have little doubt of its being the 
salt you predicted, composed of one atom oxide of iron, and 
three atoms sulphuric acid. 
I mean to continue the investigation of these singular salts ; 
and if I am so fortunate as to discover any more of their proper- 
ties, I will transmit me the results. I remain, dear Sir, 
ery sincerely yours, 
Joun Tuomas Cooper. 
ArTIcLE VII. 
ANALYSES OF Books. 
Philosophical Transactions of the Royal Soctety of London, 
for 1818, Part IT. 
(Continued from p. 218.) 
VI. Observations on the Heights of Mountains in the North of 
England. By Thomas Greatorex, Esq. F.L.S.—Mr. Greatorex, 
during the summer of 1817, measured the height of Skiddaw 
above Derwentwater by levelling. At the same time, he ob- 
served the height by an excellent mountain barometer, made by 
Ramsden, while Mr. Crosthwaite, of the Keswick Museum, 
observed another barometer, placed 10 yards above Derwent- 
water, every half hour. An observation was made by means of 
the mountain barometer during the levelling at every 50 yards of 
descent. The following are the results obtained by these differ- 
ent measurements : 
Yds. Ft. In. 
Skiddaw, above the lake. ...... | gree aatte tate 936 0 31 
Derwentwater, above the sea at low water-mark 
by Mr. Crosthwaite’s measurement .......... Tu. @ ce. 
Height of Skiddaw above the sea by levelling.... 1912 0 34 
Inches. 
Barometer below (10 yards above the lake) 30:050 therm. 61° 
Barometer above. ........2.+4 aN ee . 27°156 attached 
therm. 57°; detached ditto 50°. 
Yards, Error. 
Hence the height by Dr. Maske- 
lyne’s formula.,.......... .. 9261685  .. + 01685 
By Dr. Hutton’s formula...... ». 925-2850 — 0°7150 
At 50 yards down, 
Height by measurement ........ 876:000000 .. 
By Maskelyne’s formula........ 873°194477 ... — 2°805523 
By Hutton’s formula. ........06 _ .. — 3948000 
