[18]. It is found in a ſeparate ſtate in large quantities in ſome of our mines and wells, and is called the choak damp. In the famous Grotto del Cano too it exiſts tolerably pure. W.
[19]. D. D. Margraaf, Weigleb.
[20]. Opuſc. chem. vol. II. p. 368.
[21]. Margraaf Opuſc.
[22]. Cavendish Phil. Trans. 1767.
[23]. Dr. Home, in his eſſay on bleaching, ſays it is found in coal mines in this iſland, and a friend aſſures me that he has obtained it from the water iſſuing out of coal pits. W.
[24]. As volatile alkaly may be obtained in large quantities from pit coal, and produced by proceſſes not dependant upon putrefaction, there is reaſon to believe that the vitriolic ammoniac may be formed in ſeveral ways not noticed by the author. W.
[25]. Acta Stockh. 1772.
[26]. From ſome experiments lately made I found that both tinkal and purified borax, required twice their weight of ſedative ſalt, to neutralize them perfectly ſo that they would no longer change vegetable blues to a green. W.
[27]. Baumé mem. des ſc. etr. tom. iv.