Intelligence and Miscellaneous Articles. 325 



of iron when obtained from a filtered infusion of galls and finery 

 cinder, as above described, on being evaporated to the consistency 

 of thick molasses, gum arabic in due proportion having been pre- 

 viously added, forms a pigment which might, it is conceived, super- 

 sede Indian ink. When completely dried it glistens like jet with or 

 without the gum. 



This tanno-gallate of iron only requires to be dried and ignited 

 at a low red heat, in order to be converted into a pyrophorus. A 

 few years ago Dr. Hare ascertained that, by a similar ignition in close 

 vessels, cyanoferrite of iron, the Prussian blue of commerce, gave 

 a pyrophorus. But as the pure cyano-ferrite of iron, resulting from 

 the addition of the ferro-prussiate of potash, more properly the cy- 

 ano-ferrite of potassium, to a ferruginous solution did not form a 

 pyrophorus ; he was led to believe that the presence of sulphate of 

 alumine in the commercial Prussian blue was the source of the differ- 

 ence, probably by being converted into a sulphide of aluminium, or 

 potassium. 



The production of a pyrophorus from the tanno-gallate proves 

 that iron and carbon, when in a state of minute division, are capable, 

 by ignition in close vessels, of acquiring that property of sponta- 

 neous combustibility which entitles the body which possesses it to 

 be called a pyrophorus. 



In truth these results are consistent with some facts mentioned 

 by Berzelius, as having been ascertained by Mitcherlich, respecting 

 the spontaneous combustibility of iron, reduced from the state of 

 magnetic oxide to that of the pure metal in an extreme state of di- 

 vision. They are also consistent with the spontaneous combusti- 

 bility of the residue resulting from the ignition of the oxalate of iron 

 at a red heat. 



RAPID CONGELATION OF WATER BY MEANS OF HYDRIC (SUL- 

 PHURIC) JETHER AND CONCENTRATED SULPHURIC ACID, &C. 

 BY R. HARE, M.D. 



In freezing water by the vaporization of hydric, commonly called 

 sulphuric, aether, there is much labour in pumping, and the aetherial 

 vapour condensing in the pump, disqualifies it for nice experiments 

 until cleansed. Dr. Hare finds that the interposition of sulphuric acid 

 lessens the requisite labour, and protects the pump. By means of 

 a globe or bottle with two tubulures, and a glass funnel with a cock, 

 the acid being in the globe, the water in a retort, and the aether in 

 the funnel, while the two former are exhausted, on allowing the 

 aether to descend upon the water, the congelation of this liquid is 

 instantaneous. 



It has been ascertained by the same chemist, that a permanent 

 self-regulating reservoir of chlorine may be made by means of the 

 apparatus heretofore used by him for nitric oxide, substituting for 

 the materials used in that case, manganese in lumps and concen- 

 trated muriatic acid. 



In one case, Dr. Hare, doubting the purity of the gas, from some 



