General Account of the Niirous OxiJr, 287 



a. Healthy perfons after breathing It accurately for a minute and a half, or two minutes, 

 are ufually exhilarated, and afFeded by ftrong pleafurable fenfations, the circulation is 

 quickened, the countenance becomes darker, and a fenfe of warmth is induced. 



i. On unheaJthy perfons the efFedls are lefs pleafant, and in certain cafes it has induced 

 hyfterical affe£tions. 



c. Nitrous oxide after being breathed for more than three minutes, produces violent 

 excitement, wliich generally ends in momentary lofs of fenfation. 



d. As far as experiments have yet gone, there is no reafou to belid\fe that any notable de- 

 bility follows, even its moft violent agency. 



Seft. 2. Warm blooded animals when permanently imnierfed in nitrous oxide, live 

 longer in it than in any other gafcs, except fuch as contain free oxigen ; but cold blooded 

 animals arc quickly deftroyed by it. 



a. The fnraller quadrupeds die in pure nitrous oxide ih three or four minutes; they 

 abforb a little of the gas, and their death feems to be occafioned by exceffive ftimulatlon. 



li. When examined after death their internal parts are found to have undergone very 

 peculiar changes. 



The animal fibre is! very Inttritable ; . the blood both in the^ arteries and veins Is dark and 

 purplu, and the lungs are marked with lai^ge purple fpots. ' ' 



Se£l. 3. When nitrous oxide is expofed to fluid venous blood, "whether in the veflels 

 or out of them, it is rapidly abforbed, apparently no portion of it is decompofed, and the 

 colour of the blood becomes rather more incliiied to piirple. 



^ II. 



Obfervations on the fuppofed Magnetic Property of Nickel, iy Richard. Chevenix, E/q. 



F. R. S, and M. R.I. A. Communicated by the Author. 

 ^ io aansi? •■ 



np. 



A HE properties of magnetlfm and polarity, Jirft iobferved in iron, were, for a long tlme» 

 tbe attributes of it alone. But the experiments of later philofophers had given reafon to 

 fuppofe, that nickel and cobalt participate of both. The celebrated Bergman, in his dif- 

 fertation upon the former of thefe two metals, after lamenting the infufficiency of all his 

 attempts to deprive It of the laft portions of Iron with which it was contaminated, con- 

 cludes the paragraph with a doubt, whether niagnetifm may not be a property of nickel, 

 as well as of iron. To tliis the authority of Arvid,fon may be added ; and hence chymifts 

 have fuppofed, that magnetlfm is not a property of Iron exclufively. In Italy, within thefe 

 ifrve years, as I have been informed, compafles for marine purpofes have been made, of 

 nickel and of cobalt ; thus being preferable to iron, as better refilling the adion of the 

 air. I know it was the. opinion of tlie French chymiftsj that magnetic needles^ made of 



either 



