Method of making Shagreen at AJlracan. ni-j 



the Antiphlogiftic Chemiftry, in which you will find new 

 ideas on the acidifiable bafe of the marine acid. I am cer- 

 tain it is hydrogen ; but the acid contains much lefs oxygen 

 than water. 



That I may not leave your curiofity ungratified in regard 

 to the analyfis of azot, I muft tell vou, that it is compofed 

 of hydrogen and oxygen in the proportion of 0"3i of the 

 former, and 0*79 of the latter *: it is nothing elfe, therefore, 

 than an oxyd of hydrogen. All our eudiometry is falfe, fince 

 azot is a produftion of our eudiomctric analyfis, and did not 

 exifl: in the air before the experiment. Alumine or argilla- 

 ceous earth is the fubftance mod proper for changing atmo- 

 fpheric air into azotic gas. This is the principle on which 

 the production of faltpetre, fo much fought after in France 

 at the commencement of the war, depends, and which is 

 now difcovered by my experiments. 



Hydrogen gas may be transformed into azotic gas by re- 

 fpiration : the oxygen gas, a part of which is always con- 

 denfed in the lungs, joins itfelf to the hydrogen, and changes 

 it into azot. The fame converfion may be eft'efted, and in a 

 much more fenfible manner, by bringing hydrogen gas into 

 contadl with moiftened argil. 



VII. Defcription of the Method employed at AJlracan for 

 maliing grained Parchment or Shagreen. By Profrffhr 

 Pallas. 



X HE procels for preparing fliagreen is a very old oriental 

 invention, not praftifed in Europe, and which, as far as I 

 know, has never yet been defcribed ; thovigh Bafil Valentinf 



* In our !a(l we announced this difcovery of Dr. Giitanner, and gave 

 Dr. Van M'lns's letter to C. Delametheric upon the fiibjeft, by which the 

 proportions were ftated to be hydrogen 93, and oxygen 7. We are in- 

 clined to think the prefent is the refult obtained by later experiments, as 

 ihe former was copied from the Journal de Phyflquc for Nivofe, which 

 anfwers to the end of December and 21 days of January. Edit. 



f See M. B. Falentini Mufeitm Miifcorum cder FolljiUmlige Scbaububne 

 alter materuillien vndjfecereycny p, 439. 



Vol. VI. F f is 



