106 Odour of the Thunderbolt. 



Concerning the odours developed by the thunderbolt. 



Some philosophers have supposed that there was no necessity 

 for inquiring into the particular causes of the perceived odour 

 in each flash of lightning. They have insinuated that the ful- 

 minating matter in its more or less abundant passage through 

 the nervous papillae of our organs, may itself excite a move- 

 ment analogous to that which results from any given odour. 

 This opinion might to a certain degree be admissible if the 

 subject related only to smells which were experienced at the 

 moment. But the thunderbolt, wherever it passes, occasions, 

 even in the open air, odours which are perceptible for a long 

 time. Again, when lightning forces its way into a confined 

 situation, its passage is followed by sulphurous vapours, through 

 which the eye cannot penetrate. There is evidently, therefore, 

 some substance disseminated through the air. Are we to sup- 

 pose that these substances are carried along with the lightning 

 in its course, as were those powdery deposits examined by M. 

 Fusinieri, and which have contributed to supply a commence- 

 ment to our explanation of fire-balls ; or rather, do they pro- 

 ceed from the sudden evaporation of the different substances 

 which are contained in the new or old wood, varnished or un- 

 varnished, in the walls, stones, soils, &c. &c. through which the 

 lightning has passed ? These are points which in our present 

 state of information cannot be determined : and whatever may 

 be the fate of these proposed explanations, we must not be too 

 confident concerning the alleged uniformity of the nature of 

 the developed odour. I have found, in truth, that if, in most 

 instances, it has been stated to resemble the smell of sulphur ; 

 on other occasions it has been compared to that of phosphorous, 

 and not unfrequently to nitrous vapour. The odour of nitrous 

 gas, as will afterwards be pointed out, could more easily be ac- 

 counted for. 



Lightning instantly melts many substances, and produces immediate 

 vitrification ; it shortens those metallic wires along v^hich it runs, 

 and pierces holes in the bodies it encounters in its progress. 



The details upon these interesting topics appear in another 

 part of this essay, and I have here but few general remarks to 

 offer concerning them. I must observe, however, that we are 



