406 More Vital Air m Summer than Winter. [Book V. 



From the great confumption of oxygen by various 

 natural and artificial procef es, it might be expected 

 that a deficiency of this fluid in the atmofphere might 

 fometimes occur ; but the wifdom of Providence is 

 evident in this, as well as in every other inftance ; for 

 we have already feen that the proceiTes in nature which 

 deftroy this air are nearly balanced by thofe which 

 produce it. A feries of experiments were made at 

 Stockholm by the indefatigable Scheele, to afcertain 

 the goodnefs of the air during every day in the courfe 

 of a year. He found that the diminution by the eudio- 

 meter never exceeded one-third, nor was lefs than eight 

 thirty-thirds. The quantity of vital air was lead in 

 March, November, and December, and in general lefs 

 in the winter than in the fummer months, which may 

 be attributed to the redundant fupply of this matter 

 by the copious vegetation which takes place at that 

 period. The air at fea is generally found in a purer 

 ftate than at inland places. 



Extraordinary as this mixture of fluids in the at- 

 mofphere may appear, it is eiTential to' our health, and 

 even our exiftence, and demonftrates no lefs the wif- 

 dom and goodnefs of Providence, than all his other 

 beneficial appointments. This pure vital air, fays 

 Briton, fo wholefome, fo necelTary in a moderare quan- 

 tity , like fpirituous liquors, or falutary medicines, muft 

 be ufed with precaution, and would be fatal in the ex- 

 cefs. If we weve indeed to breath pure or oxygen 

 air without any mixture or alloy, we mould infallibly 

 perifli by the unnatural and fatal accumulation of heat 

 in our bodies , ii, again, the whole atmofphere was 

 compoied only of vital air, combuftion would not pro- 

 9eed in that gradual and moderate manner which is 

 neceilary to the purpofes of life and of focietyj and 

 even iron, and the metals themfelves, would blaze with 



a rapidity 



