316 Scientific Intelligence. [April, 



III. Dcebereiner's Eudiometer. 



Prof. Dcebereiner having suggested the use of finely divided platina 

 for the purpose of detecting minute portions of oxygen in a gaseous 

 mixture, in which hydrogen also is present, Messrs. Daniell and Chil- 

 dren mixed 20 measures of atmospheric air, with 37 measures of hydro- 

 gen gas, and passed up to the mixture a small portion of the platina 

 powder, procured by heating the ammonia muriate to redness, and 

 made into a ball with precipitated alumina. The pellet was heated red 

 by the blowpipe, immediately before it was used ; its size about that of 

 a small pea. The absorption amounted to 13 measures = 4'3 oxygen, 

 being 01 of a measure more than the quantity of oxygen in 20 mea- 

 sures of atmospheric air, which may probably have arisen from a slight 

 impurity in the hydrogen, or from some minute unperceived bubbles 

 of air, entangled in the mercury. 



Another mixture of common air and hydrogen, in which the latter 

 was in considerable excess, was deprived of its oxygen by the pellets, 

 and when the absorption was complete, 38 measures of the residual gas 

 were taken, and a fresh pellet, heated to redness, immediately before 

 it was used, passed up. After standing about a quarter of an hour, no 

 absorption had taken place. The tube and the mercury were then 

 placed before the fire, till the whole apparatus was too hot to be 

 touched with the naked hand. It was then removed from the fire, anil 

 when cooled to its original temperature, the mixture occupied, as 

 before, exactly 38 measures. The powder of platina with hydrogen 

 seems, therefore, to be admirably calculated for eudiometrical purposes. 

 Its application is extremely simple and easy, it is speedy in its effect, 

 and no error need be apprehended from the formation of ammonia, 

 even at considerably elevated temperatures. It appears also to be 

 well calculated for ascertaining the purity of simple gases, at least as 

 far as regards admixture of atmospheric air. The oxygen of a very 

 minute portion of common air, mixed with carbonic acid gas, and a 

 little hydrogen, was immediately absorbed, on passing up one of the 

 little pellets to the mixture. — (Institution Journal, xvi. 374-.) 



IV. A T tu> Minerals. 



Mr. Brooke has lately described two new mineral bod'es ; to the 

 first he has given the name of Childrenite, on account of the attention, 

 among other inducements, which Mr. Children has shown to mineral- 

 ogical chemistry. This mineral was met with in Devonshire, and was 

 said to have been taken from some part of the ground which had been 

 perforated for the Tavistock canal ; it was supposed at first to be car- 

 bonate of iron ; but Dr. Wollaston determined that it was a phosphate 

 of alumina and iron. 



The primary form of the crystal is assumed by Mr. Brooke to be a 

 right rhombic prism ; but he has not succeeded in cleaving it. The 

 crystals scratch glass ; their colour is wine-yellow, they occur on the 

 surface of crystallized quartz, and might be mistaken by a casual 

 observer for sulphate of barytes. 



The next mineral was sent, among other Vesuvian substances, to 

 Mr. Brooke by Dr. Somerville, from which circumstance he has named 

 it Somervillite ; the primary form of the crystal is a right square prism, 

 but the crystals are modified by numerous secondary planes ; they may 



