Letts & Bhake—The Carbonic Anhydride of the Atmosphere. 211 
Frankland, in 1861, investigated the amount in the neighbour- 
hood of Mount Blane with the following results— 
Chamounix (3446 ft.), 5 ; 5 Oso 
Grand Mulets (10,007 it.), . ; > Mile 
Mount Blane (summit 15,784), . 6 9 Cl 
Angus Smith, in 1863, made a number of determinations in 
the air of Scotch mountains giving the mean results— 
Summits, . ; : : : 5) «Oey 
Bases, i : : : . ds 41 
He also gives the following figures— 
Height below 1000 ft., 5 : 5) BB 
55 of 1000-2000, . : . 3°34 
AS of 2000-38000, . ; . 93°32 
over: OU00K) ; : . 9336 
In 1878 Truchot obtained the following results :— 
Altitude COz in 10000 vols. air. 
Clermont Ferrand, : : SOD Ws 6 Ge 
Summit Puy de Dome, . 1446m. . 5) 203 
Bs Pic de Sancy, al S84) mee. 5 i872 
Two years later Tissandier during ascents in the balloon “ Le 
Zénith,”’ found 2°4 at an altitude of 800m., and 3:0 at 1000 m., 
but pointed out that no definite conclusions could be arrived at 
until more numerous observations had been made. 
Mintz and Aubin in 1881 were unable to find any appreciable 
difference between the amount of carbonic anhydride in the air 
on the Pic du Midi (2877 m.), and in the neighbouring valleys. 
As a mean of fourteen determinations 2°86 were found on the first, 
and as a mean of three determinations 2°82 in the second. “ All 
the figures we have obtained,” they say, ‘‘ approximate those found 
in the inferior part of the atmosphere both by ourselves as well as 
by Reiset and Schulze at very varied stations. In our experi- 
ments on the Pic du Midi the direction of the wind, and the state 
of the atmosphere experienced variations: we have then worked 
under diverse conditions, yet the proportion of carbonic anhydride 
has remained sensibly constant.” 
