Cafeou! Oxyd if jfzote found to he Refpirahk. ^j 



known ; for the fubfequent operations may then be properly conduced, and the inconve- 

 nience attending the ufe of fome of thefe falls may be prevented. This no doubt is a lead- 

 ing advantage pofiefled by the man of information, beyond the fimple operative artift, who is 

 incapable of varying his procefTss according to the nature and flate of the falts he may ufe. 



I fliall confine this paper to accounts of the colour obtained from the oxyde of iron : 

 I. When it is ufed alone upon goods which have received no previous preparation, and, 2. 

 when it is employed jointly with the red of madder, on a piece prepared to receive the Adri- 

 anople red. 



I. If fulphate of iron or any other martial fait be diffolved in water, and cotton be plunged 

 therein, it will acquire a chamois tinge, more or lefs deep, accordingly as the folution may be 

 charged with the fait. The affinity of cotton with the iron is fuch, that it attrafts the 

 metal, and takes a great part from the acid which held it in folution. 



(To be concluded in our kext.) 



SCIENTIFIC NEWS, afc, 

 Refplrabilky of the Gafeous Oxyd of Azote^ 



.1 



E^tttaH of a Letter from Mr. H. DArr.— Dated, Clifton^Jpril 17, 1799. 



HAVE this day made a difcovery, which, if you pleafe, you may announce in your Phy- 

 sical Journal, namely, that the nitrous phofoxyd or gafeous oxyd of azote, is refpirable 

 whenperfedly freed from nitric phofoxyd (nitrous gas;. It appears to fupport life longer than 

 common air, and produces cfFedb which I have no time to det..il at prefent. Dr. Mitchill's 

 theory of contagion is of courfe completely overturned ; the miftake of Prieftley and the Dutch 

 chemifts, probably arofe from their having never obtained it pure. I am now preparing a 

 paper on this fubjeft, for the next volume of tne Weft-country Contributions." 



In a fubfequent communication, Mr. Davy expreffes his appreheiifion, left a general notice 

 of the refpirability of gafeous yxyd. of azote fhould induce anyone to make injurious ex- 

 periments on himfelf, and therefore wiihes it ftiould be added, that the circumftances of fafety 

 and of hazard will be fpeedily pointed out to the public. A train of experiments, by which he 

 hopes to clear up this perplexed fubjed, are in progrefs ; and he is the more folicitous that this 

 general notice fliould be publiftied, becaufe fome moft remarkable phenomena witneffed by 

 divers perfons, in the pneumatic inftitution, and leading to ufeful pra6lices, have been a good 

 deal talked of at Briftol, and an erroneous anticipation may get into print, before the true 

 account can be prepared. 



I under- 



