224 ANNUAL OF SCIENTIFIC DISCOVERY. 



level, is a cup, from the bottom of which a curved pipe leads to the lowest 

 portion of the mould; the opening of this pipe in the cup is closed by a plug. 

 Each time this mould is to be used, it is first heated to cherry heat that is, 

 from 2000 to 2500 --in a proper oven. The air contained in the several 

 portions of the mould, expands to about fifteen times its original bulk, and 

 in so doing, escapes through the valve at the top of the air-chamber. The 

 mould is swiftly taken from the oven, the melted steel poured into it, and it 

 is replaced in the oven till the metal is congealed and brought down to 

 cherry red. From the shape of the mould, it results that the melted metal 

 entering the mould from below, pushes out the small portion of air remain- 

 ing, without mixing with it; as for the few bulbs which might have entered 

 the steel when falling down the pipe in its way from the cup to the bottom 

 of the mould, it is very little, and all collects in the sprue formed in the pas- 

 sage to the air-chamber, which is afterward broken off. After the metal is 

 congealed, it is taken from the mould and plunged into oil at 1-30. This 

 hardens it to the right point, and the articles do not require tempering, 

 beside being smooth, without cracking or warping. New York Tribune. 



NEW PROCESS FOR PREPARING INFLAMMABLE PHOSPHURETTED 



HYDROGEN. 



This process, which is completely free from danger, is based on the action 

 which cyanide of potassium in powder is capable of exerting on hydrated 

 phosphuret of copper, obtained in the humid way. The latter compound is 

 procured by decomposing, at the boiling temperature, a solution of sulphate 

 of copper by means of phosphorus ; the product constitutes a powder of a 

 grayish black, composed of phosphuret of copper and basic phosphate. 

 This powder is kept under water. When it is dried, it may with impunity be 

 mixed with cyanide of potassium; the disengagement takes place only when 

 a little water is added. 



The cyanide of potassium cannot be replaced by potassa or soda, and 

 water should not be replaced by dilute alcohol. In the former case, no dis- 

 engagement occurs ; in the second, uninflammable phosphuretted hydrogen 

 is developed. 



It is known that phosphuretted hydrogen readily blackens solutions of 

 nitrate of silver. M. Boettger applies this reaction to the production of a 

 kind of sympathetic ink; for this purpose, it is sufficient to expose to the 

 disengagement of gas a paper on which characters have been traced in a 

 solution of nitrate of silver; the characters immediately appear black, and 

 are very stable, resisting not only the action of alkaline liquors, of solutions 

 of cyanide of potassium or hypochlorite of lime, but also the influence of 

 dilute sulphuric nitric, or hydrochloric acid. 



The amorphous phosphorus reduces sulphate of copper only in as much 

 as it still contains ordinary phosphorus. The author proposes to turn this 

 property to account in industry for freeing amorphous phosphorus from the 

 ordinary phosphorus which it may contain, if we do not prefer to have 

 recourse to the very simple and practical process of separation, which M. E. 

 Nickles has made known. 



The phosphuret of copper in question is composed according to the for- 

 mula Ph Cm. In the crude state it is mixed with the basic phosphate of 

 copper, which does not impede the disengagement of phosphuretted hydro- 



