THE EARTH. 127 



empted from this general state of dissolution ; it is never found to con- 

 tract rust, though exposed never so long ; the reason of this seems tr; 

 be, that sea-salt, which is the only menstruum capable of acting upon, 

 and dissolving gold, is but very little mixed with the air ; for salt bo- 

 ing a very fixed body, and not apt to volatilize, and rise with heat ; 

 there is but a small proportion of it in the atmosphere. In the elabo- 

 /atories, and shops, however, where salt is much used, and the air is 

 impregnated with it, gold is found to rust as well as other metals. 



Bodies of a softer nature are obviously destroyed by the air.* Mr- 

 Boyle says, that silks brought to Jamaica, will, if there exposed to the 

 air, rot, even while they preserve their colour; but if kept therefrom, 

 they both retain their strength and gloss. The same happens in Bra- 

 sil, where their clothes, which are black, soon turn of an iron colour ; 

 though, in the shops, they preserve their proper hue.t In these tropi 

 cal climates also, such are the putrescent qualities of the air, that 

 white sugar will sometimes be full of maggots. Drugs and plasters 

 lose their virtue, and become verminous. In some places they are 

 obliged to expose the sweetmeats by day in the sun, otherwise the 

 night air would quickly cause them to putrefy. On the contrary, 5* 

 the cold arctic regions, animal substances, during their winter, * 

 never known to putrefy ; and meat may be kept for months witho*. 

 any salt whatsoever. This experiment happily succeeded with th- 

 eight Englishmen that were accidentally left upon the inhospitab*' 

 coasts of Greenland, at a place where seven Dutchmen had perish- 

 but a few years before ; for killing some rein-deer for their subsistenc 

 and having no salt to preserve the flesh, to their great surprise the$ 

 soon found it did not want any, as it remained sweet during their eight 

 months' continuance upon that shore. 



These powers with which air is endued over unorganized substances, 

 are exerted in a still stronger manner over plants, animals of an infe- 

 rior nature, and, lastly, over man himself. Most of the beauty, and 

 the luxuriance of vegetation, is well known to be derived from the be- 

 nign influence of the air : and every plant seems to have its favourite 

 climate, not less than its proper soil. The lower ranks of animals al- 

 so, seem formed for their respective climates, in which only they can 

 live. Man alone seems the child of every climate, and capable of 

 existing in all. However, this peculiar privilege does not exempt 

 him from the influences of the air ; he is as much subject to its malig- 

 nity, as the meanest insect or vegetable. 



With regard to plants, air is so absolutely necessary for their life 

 and preservation, that they will not vegetate in an exhausted receiv- 

 er. All plants have within them a quantity of air, which supports and 

 agitates their juices. They are continually imbibing fresh nutriment 

 from the air, to increase this store, and to supply the wants which 

 they sustain from evaporation. When, therefore, the external air is, 

 drawn from them, they are no longer able to subsist. Even that 

 quantity of air which they before were possessed of, escapes through 

 their pores, into the exhausted receiver ; and as this continues to be 

 pumped away, they become languid, grow flaccid, and die. However 



* Buffon, vol. iii. p. 62. t Ibid, vol. iii. p. 68. 



