THE REDUCTION OF NITROSOSULPHATES. 



289 



by Luxmoore that then the salt rises of itself to about 130° before it 

 explodes. 



By the above observation, Luxmoore has cleared away a difficulty 

 in Pélouze's description of the nitrososulphat.es, but has raised another, 

 without, in our judgment, having reason for so doing. Because he 

 has found the salt to lose 2^ per cent, in five minutes, when at a 

 temperature a little below 105°, he considers it impossible to explain 

 how Pélouze could have found it not to lose weight at all. But the 

 rate of loss varies greatly. In another of his experiments, it was little 

 more than half as fast as the rate just quoted ; while our observation 

 had shown that the loss need be only, 10 per cent, in 2\ hours, and 

 this seems to explain how Pélouze might have failed to notice suf- 

 ficient loss to be deemed worth recording. We have only to assume 

 that he exposed his salt to heat for only a. short time and in a very 

 dry atmosphere, and that he attributed the slight loss, that, even 

 then, must have occurred, to the presence of a little moisture in his 

 salt, as prepared. No doubt, the salt loses weight rapidly when 

 heated in ordinary damp air ; in such air it slowly loses weight even 

 at the common temperature, while the sodium salt does so rapidly. 

 But in a well-dried atmosphere, either of air or hydrogen, as in our 

 experiments was used, the well-dried powdered salt loses weight much 

 more slowly ; so that it becomes probable that, with absolute dryness 

 of salt and atmosphere, there would be no loss at all. It is surely 

 on account of dampness of the salt, that the rate of loss is most 

 rapid at first, as Luxmoore rightly observed ; and we must there- 

 fore, also, nssume that Pélouze worked upon a well desiccated salt. 



In concluding this paper, we would call attention to the small 

 part which Sir Humphry Davy had in the discovery of the nitroso- 

 sulphates, so small that we must demur to the custom, which prevails, 

 of naming him as their discoverer, as being an injustice to the 



