432 Intelligence and Miscellaneous Articles. 



showed that here the acid must be supposed capable of combining 

 with an indefinite or indeed an infinite amount of water, while in 

 other cases again, bodies (such as sugar for instance) exercise no 

 effect upon the water and do not seem to combine with, but only to 

 be dissolved in it. The former is an instance of a continuous and not 

 intermittent sort of combination ; and though we need not anticipate 

 a recurrence of the controversy of BerthoUet and Proust, yet this 

 shows us that the actions of quantity or mass so dwelt on by the 

 former are not without a great significance ; and that the power that 

 can thus enable us to determine such important points in chemical 

 statics, is well worthy of the attention of the philosophic mind, 



LX. Intelligence and Miscellaneous Articles. 



ON THE PHOSPHORESCENCE OF CHALK STREAKS. 

 n|"^HE phosphorescence of streaks made with chalk upon a warm 

 -l tile is brought forward by Mr. Napier, in the March Number of 

 the Philosophical Magazine, as opposed to the views recently published 

 by Dr. Draper. It seems, however, to originate in a totally foreign 

 cause. If the tile be placed on the cap of a gold-leaf electroscope, 

 the leaves diverge as soon as the sti'eak is made. All writers on 

 phosphorescence have carefully distinguished between the emission 

 of light by phosphorescence and by electricity. Thus, as Dr. Dra- 

 per's paper states, a diamond rubbed on gold will emit light, but it 

 will also shine after exposure to the sun. In the former case, it will 

 attract a hair or other light body ; in the latter it will not. When- 

 ever friction is required for luminosity, we may reasonably suspect 

 electrical disturbance. Thus two pieces of quartz or sugar, rubbed 

 together, shine ; and the electroscope shows one to be positive and 

 the other negative. Quicksilver in an exhausted tube will emit a 

 milky glow on the slightest motion, an experiment formerly described 

 by Homberg as a phosphorus. Pieces of mica suddenly split asunder, 

 a stick of sealing-wax snapped across, dry paper torn, or an air-gun 

 discharged in the dark, produce light ; but none of these are cases 

 of what is meant by phosphorescence. Mr. Napier's experiment 

 belongs to the same class, and does not seem in any manner to bear 

 on the views of Dr. Draper. 



OBSERVATIONS ON NITROUS ACID AND THE SOLUTION OF NITRO- 

 SULPHURIC ACID. BY M. GUINON. 

 In searching for the cause of an accident which happened to silk 

 coloured rose by ammoniacal cochineal, and by which it was sud- 

 denly decolorized, this was found to have been due to the presence 

 of nitrous acid in the sulphuric acid employed. M. Guinon states, 

 that he was certain that, if the sulphuric acid had been pure, it would 

 not have altered the ammoniacal cochineal, even after several days 

 of contact ; he had made the experiment frequently. The nitrous 

 acid itself merely turns the colour of an orange-red, without destroy- 

 ing it. The reaction observed could then be attributed only to the 



