Life of Sir Humphry Davy. 351 



Dr. Paris has given an outline of these extraordinary essays, to 

 which we must refer the reader. 



The letters of Davy at this period to his friend, Mr. Davies 

 Gilbert, give an interesting- account of his experimental pursuits. 

 The accidental observation, that two pieces of bonnet cane rubbed 

 together produced a faint light, led him to examine into the cause. 

 On removing the epidermis, he found that no light was produced ; 

 and subjecting the epidermis to chemical analysis, it proved to have 

 all the properties of silex: the similar appearance of the epidermis 

 of reeds, corn-straw, and grasses, induced him to suppose that they 

 likewise contained silex ; by burning them carefully and analysing 

 their ashes, he found they contained it in larger proportions than 

 the canes, and that the straws and grasses contain sufficient potash 

 to form glass with their flint. He says, * A very pretty experiment 

 may be made on these plants. If you take a straw of wheat, 

 barley, or hay, and burn it, beginning at the top, and heating the 

 ashes with the blue flame, you will obtain a perfect globule of hard 

 glass fit for microscopic experiments.' It was at this period that 

 he was led by the nature of his engagements at Bristol to com- 

 mence his inquiries into the nature of nitrous oxide, and the results 

 enabled him to give to the world the first satisfactory account of 

 the combinations of oxygen and nitrogen. These he published in a 

 distinct volume, in the year 1800, under the title of * Researches, 

 Chemical and Philosophical, chiefly concerning Nitrous Oxide and 

 its Respiration/ 



' The close philosophical reasoning, ' (says Dr. Paris,) ' the patient 

 and penetrating industry, the candid submission to every intimation of 

 experiment, and the accuracy of manipulation, so remarkably displayed 

 throughout this work, have rarely been equalled, and perhaps never 

 surpassed. What shall we say of that spirit, which led him to inspire 

 nitrous gas at the hazard of filling his lungs with the vapour of aqua 

 fortis ! or what of that intrepid coolness, which enabled him to breathe 

 a deadly gas [carburetted hydrogen], and to watch the advances of its 

 chilling power in the ebbing pulsations at the wrist ? ' 



Dr. Paris gives an amusing account of the effects which the 

 breathing of nitrous oxide produced on several scientific and lite- 

 rary friends of Davy, and thinks that, though the fact is established, 

 that the gas possesses an intoxicating quality, the enthusiasm of 

 persons submitting to its operation has imparted a character of 

 extravagance to its effects not quite consistent with truth. Davy 

 had nearly fallen a victim to his temerity, in breathing three quarts 

 of hydro-carbonate, mingled with nearly two quarts of atmospheric 

 uir. This daring experiment, Dr. Paris thinks, if the precautions it 

 suggests be properly attended to, may become the means of pre- 

 serving human life, and is also valuable, as affording support to 

 physiological views, with which its author was probably not ac- 

 quainted. It is important, inasmuch as it proves that, in cases of 

 asphyxia, or suspended animation, there exists a period of danger 



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