1817.] éo the Summit of Mount Blanc. 103 
menting pain in my face and eyes. My face was one continued 
blister, and my eyes I was unable to open ; nor was I without ap- 
prehensions of losing my sight for ever, till my guides told me that 
if I had condescended to have taken their advice of wearing, as 
they did, a mask of black crape, the accident would not have be- 
fallen me, but that a few days would perfectly restore the use of my 
eyes, After I had bathed them with warn water for half an hour, 
I found to my great satisfaction that I could open them a little, on 
which I determined upon an instant departure, that I might cross 
the Glaciere de la Coté before the sun was risen sufficiently high for 
its beams to be strongly reflected fromthe snow. But unluckily the 
sun was already above the horizon ; so that the pain of forcing open 
my eyes in the bright sunshine, in order to avoid the chasms, and 
other hazards of my way, rendered my return more irksome than my 
ascent. Fortunately one of the guides, soon after I had passed 
the glaciere, picked up in the snow a pair of green spectacles, 
which M. Bourrit had lost, and which gave me wonderful relief. 
At eleven o’clock on Aug. 10, after an absence of 52 hours, of 
which 20 were passed in the hut, I returtied again to the village of 
Chamouni. From the want of instruments (the scale of the baro- 
meters I had being graduated no lower than 20 inches, which was 
not sufficiently extended) the observations I made were but few. 
Yet the effects which the air in the heights I visited produced on the 
human body may not perhaps be considered as altogether uninte- 
resting, nor will the proof I made of the power of the lens on the 
summit of Mount Blane, if confirmed by future experiments, be 
regarded as of no account in the theories of light and heat. At any 
rate, the having determined the latitude of Mount Blanc may assist 
in some particulars the observations of such persons as shall visit it 
in future ; and the knowledge which my journey has afforded, in 
addition to that which is furnished by M. de Saussure, may facilitate 
the ascent of those who, with proper instruments, may wish to 
make in that elevated level experiments in natural philosophy.* 
Artic.te II. 
On the Acids contained in the Juice of the Stems of Rhubard. 
By M. Donovan, Esq. 
Durine my investigation of the nature and combinations of the 
sorbic acid, I had occasion to examine a great variety of vegetable 
* As the suinmitof Mount Blanc bears from Neuchatel by the compass 20° 54‘ 
01’ W., by using the difference of latitude and the true bearing, the longitude in 
space is 3’ 10” W. of Neuchatel, and consequently 7° 6! 50” H, from Greenwich, 
(See Annals of Philosophy, y. 368.) 
