Lerrs & BuaKke— The Carbonic Anhydride of the Atmosphere. 175 
cause of increase is no doubt to be found in the combustion of fuel 
and illuminants, but the respiration of men and animals, the decay 
of refuse, &c., are also important sources of evolution. 
Boussingault, in a paper published in 1844,' calculated that 
the following quantities of carbonic anhydride in cubic metres 
were thrown into the air of Paris every twenty-four hours :— 
By the population, 5 c 9 é 336,777 
», horses, : ; : P : 182,370 
», wood burnt, : : : : é 855,385 
>, Charcoal burnt, : i ‘ F . 1,240,700 
>> pit coal burnt, ‘ ; F ; 314,215 
», wax burnt, j P 5 ‘ : 1,071 
», . tallow burnt, ; i : . : PY5) {| ps 
»; oil burnt, : : 2 : ‘ 28,401 
Total, : : . 2,944,641 
(giving the ratio of carbonic anhydride produced by combustion 
to that owing its origin to respiration of about 5:1). He then 
goes on to calculate that if this amount was suddenly thrown into 
the air of Parisit would form a layer nearly +15 metre deep. 
It is interesting to carry this calculation further. 
Boussingault found 4:0 parts of carbonic anhydride per 10,000 
in the air of Paris, and we now know that the average for country 
air is about 3:0. If Boussingault was correct, Paris air (like 
Londen air) contains + more carbonic anhydride than fresh air, or 
we may state the case this way :— 
1 cubic metre of ‘‘fresh’’ air contains ‘ j 0°3 litres CO2 
99 99 be) be) Paris 5)5) 9? o s 0 0-4 99 99 
Difference, 5 OFT ae 
But if all the carbonic anhydride generated in Paris were thrown 
suddenly on to the surface of the ground each cubic metre of the 
air there would contain 100°0 litres; but as the actual increase is 
0-1 litres per cubic metre, it follows that the total average effect is 
the dilution of the carbonic anhydride thrown into the Paris 
atmosphere 1000 times by fresh air, the latter receiving an 
addition of 33°3 per cent. in the process. 
It is possible that Boussingault’s estimate of the carbonic 
anhydride in Paris air istoo high, and that the difference between 
1 Annales de Chimie et de Phys. [3], 10 [1844], p. 461. 
