TRANSACMONS OF THE SECTIONS. 55 



some extent even in strong alcohol. In forming this salt, if platinum solution con- 

 taining acids of nitrogen be used, chlorplatiuate of ammonium is obtained. In 

 using platinum black, dark-colom-ed products are formed, which partly remain 

 with the platinum, and interfere with the process. The author has tried all the 

 other forms of platinum, and they all act more or less ; but finds that platinized 

 charcoal is the best. He prefers cocoanut-shell charcoal, because of its greater 

 absorptive power ; but ordmary charcoal, containing the same proportion of pla- 

 tinum, 5 per cent., answers very well. 



Hydrogen from dilute sulphuric acid and zinc is passed through a wash-bottle, 

 then through a cyanogen-bottle (giving oft' cyanogen from the mixture mentioned 

 above). The mixed gases pass then through a wash-bottle containing water, then 

 through an empty bottle, then through a long calcium-chloiide tube to dry them 

 thoroughly. They then pass over the heated charcoal placed in a flask or in a tube 

 bent into a convenient form, and heated in an air-bath to 190° to 200° C, accord- 

 ing to the rapidity of the current of the gases. 



When this apparatus is working, dense white fumes are seen in the Liebig's 

 bulb containing dilute hydrochloric acid, through which the gases finally pass. 

 With a sufficient excess of hydrogen, little cyanogen escapes unacted on ; and 

 the charcoal remains as efficient after some days' use as at first. 



This platinized charcoal also serves well for the hydrogenatiou of hydrocj^anic acid. 



Ordinary charcoal possesses in some degree the property of causing the gases to 

 combine at a temperature of 210° C. 



III. Cyanogen Hydriodate. — This substance is obtained by bringing the two dry 

 gases into contact — more conveniently by passing cyanogen into dry ether, and then 

 saturatiog it with dry hydriodic acid gas. It crystallizes out diu-ing the process. 

 It has a reddish-yellow colour and onion-like smell, and stains the skin, paper, &c. 

 dark brown. It absorbs moisture from the air with avidity, and is decomposed by 

 water and by alcohol. From the aqueous solution the iodine is entirely precipi- 

 tated by argentic nitrate. It is dried and freed from ether by passing over it a 

 current of diy hydrogen while the flask containing it is placed on the water-bath. 

 Heated above 100° C. it decomposes, giving off free iodine. Analyses give per- 

 centages agreeing well -with the formula Cj N^ Hg I3. 



A compound containing more 11 I than the above exists, but is exceedingly im- 

 stable, continually losing hydriodic acid at ordinary temperatures. 



These substances were obtained while experimenting on the hydrogenation of 

 cyanogen by the action of metals on cyanogen and excess of hydriodic acid ia 

 etherial solutions. 



Note on the Distillation of Sulphuric Acid. By Thomas Faikley, F.O.S. 



In an attempt to obtain sulphuric anhydride by distilling sodium anhydrosulphate 

 with strong sulphuric acid, the author observed the great facility with which sid- 

 phuric acid boils and distils in the presence of alkaline sulphates. By heating sul- 

 phuric acid and some alkaline sulphate over an ordinary Bunsen rose-burner, in a 

 glass retort sheltered simply from draughts of cold air, quantities of pure sulphuric 

 acid may be readily obtained. If the sulphuric acid contains acids of nitrogen, as it 

 should do when an acid free from arsenic is required, these come over first, along 

 with any water that may be present. Lead sulphate crystallizes out during the 

 process, but does not interfere till it has accumulated from repeated operations. 



On the Furification of SanJcey Brook. Bi/ Alfred E. Fletcher, F.O.S. 



The Sankey Brook flows through St. Helens, in Lancashire. Its chief impuri- 

 ties are free acid and sulphide of hydrogen. 



The author proposes to allow the water to flow over beds of the old alkali waste, 

 which is to be found in immense quantities in the neighbourhood. 



This, containing hyposulphite of calcium, would give oft" sulpliurous acid when 

 .dissolved in the acid water of the brook, and thus destroy the sulphide of hydrogen, 

 the two gases forming together sulphur and water; at the same time the lime 

 •would neutralize the free acid. 



