6q8 philosophical transactions. [anno 1790. 



same apparatus, and in the same circumstances, taking care always to add more 

 metal than could be dissolved, that, by weighing the remainder, the quantity 

 capable of being dissolved might be found, as I had done with the experiments 

 on silver: and the results were as follow. 



11. No tin was dissolved nor calcined by the mixtures in the proportion of 

 200 grain-measures of oil of vitriol to 200 grs. of nitre; nor by any other mix- 

 ture in the proportion of 200 grain-measures of oil of vitriol to 150 grs. of 

 nitre, and consequently no gas was produced in either instance. 



12. With a mixture in the proportion of 200 grain-measures of oil of vitriol 

 and 100 grs. of nitre, the tin began soon to be acted on, and to be diffused 

 through the liquor; but no extrication of gas appeared till the digestion had 

 been continued 2 hours in boiling water; and then it took place, and gave a 

 frothy appearance to the mixture, which was of an opaque white colour, from 

 the powder of tin diffused among it. In this experiment the quantity of tin 

 thus calcined was 73 grs., and the quantity of nitrous gas extricated during this 

 action on the tin was 8500 grain-measures. Then, on pouring 200 grs. of water 

 into the retort, a fresh effervescence took place between the water and the white 

 opaque mass, and 4600 grain-measures of nitrous gas were thrown into the in- 

 verted receiver. 



13. With a mixture in the proportion of 100 grain-measures of oil of vitriol 

 to 30 grs. of nitre, 30 grs. of tin were dissolved or calcined, and the nitrous gas, 

 which began to be extricated much sooner than in the last-mentioned experiment 

 with a larger proportion of nitre, amounted to 6300 grain-measures. Water, 

 added to this solution of tin, did not produce any effervescence. 



14. With a mixture in the proportion of 200 grain measures of oil of vitriol, 

 200 grs. of nitre, and 200 grs. of water, 133 grs. of tin were acted on with an 

 effervescence, which took place violently, and produced 6500 grain-measures of 

 nitrous gas. 



15. The several mixtures above mentioned, in different proportions of nitre 

 and oil of vitriol, did, by the help of the heat of the water-bath, calcine mer- 

 cury into a white or greyish powder. Nickel was also partly calcined and partly 

 dissolved by these mixtures. I did not perceive that any other metal was affected 

 by them, excepting that the surfaces of some of them were tarnished. 



16. These mixtures of oil of vitriol and nitre were apt to congeal by cold, 

 those especially which had a large proportion of nitre. Thus, a mixture of 

 1000 grain- measures of oil of vitriol and 480 grs. of nitre, after having kept 

 fluid several days, in a phial not so accurately stopped as to prevent altogether 

 the escape of some white fumes, congealed at the temperature of 55° of Fahren- 

 heit's thermometer; whereas some of the same liquid, having been mixed with 

 equal parts of oil of vitriol, did not congeal with a less cold than 45°. The 



