Intelligence and Miscellanies. 367 



feient occasions, known the phenomena to vary much in ac- 

 tivity ; iiaving in some instances seen the phosphorus thrown 

 vip agciinst the celHng of my laboratnrv. Ii was therefore 

 known to me, and I presume it is generally known to chem- 

 ists, that the reaction of the substances employed in the case 

 above mentioned is Uable to become explosive. According- 

 ly in giving directions for making phosphoric acid by means 

 of nitric acid, the necessity of a very cautious and gradual 

 addition of the phosphorus is usually mentioned, but that an 

 explosion so violent as that which I have described, could 

 arise, under the circumstances in question, I was not led to 

 apprehend, either from my reading or experience. 



I ascribe the result to the extraordinary strength of the 

 acid employed, probably caused by using in the evolution of 

 it from nitre, one half more of sulphuric acid than the equiv- 

 alent proportion, with a view of rendering the residuum less 

 difficult to remove from the retort. The presence of an ex- 

 cess of sulphuric acid, reduces the water in the nitric acid to 

 a minimum. 



REMARKS BY THE EDITOR. 



I am pleased that the above facts and cautions have been 

 communicated by D.. Hare to the public; and it may per- 

 haps, add to their effect, if I state, that I saw a similar ex- 

 plosion at a public lecture of Dr. Woodhouse in Philadel- 

 phia, in 1803 or 4, and also at one of Dr. Pearson in London, 

 in 1805 : the burning phosphorus was thrown about, and as 

 the occurrence was unexpected to both gentlemen, they 

 apologised to their hearers for the explosion. 



I will here give an extract from the MS of my Chemical 

 Text Book, now in the press. 



" Phosphorus is converted into phosphoric acid by the ac- 

 tion of the nitric acid : if weak, it merely boils, with red fumes 

 of nitrous acid ; if very strong, and especially if warm, it burns 

 with a splendid combustion : it is thi'own about in jets of fire,, 

 and requires great caution : to render it the most beautiful, 

 a tall narrow deep vessel should be used, but when the quan- 

 tity of both substances is considerable, there is sometimes a 

 dangerous explosion."* 



* This circumstance has happened so often, in my own experience, with ni- 

 tric acid distilled from very pure nitre, and without any water in the receive?' 

 that I cannot but repeat the caution that the operator should be much on his 

 guard. With a stick of phosphorus as long as a finger, dropped into two or 



