Chemical Science. 381 



quantity of substances used, is not stated. — Giornale di Fisica, 

 V. 285. 



8. Production of Cyanurets. — Cyanogen, according to M. 

 Brunner, is formed whenever a potash salt with a vegetable acid 

 is burnt with nitre : — ten parts of cream of tartar with one of 

 nitre, or two parts of acetate of potash with one of nitre, when 

 burnt, leave a product containing a notable proportion of cyan- 

 ogen. It has been shewn by M. Pagenstecher, that when eight 

 parts of nitre and five parts of tartar are burnt together, am- 

 monia is formed . 



9. Iodide of Nitrogen. — M. SeT\i[\a.s describes the following 

 process, for the preparation of this detonating compound. Form 

 a sub-chloride of iodine, to which, add ammonia in excess ; 

 muriatic acid is formed, and the iodine is almost entirely com- 

 bined with the nitrogen, scarcely any hydriodate of ammonia 

 being formed. The solid substance produced, is to be thrown 

 on a filter, washed, and dried carefully. In the usual method, 

 scarcely a fourth part of the iodine enters into combination 

 with the nitrogen. — Ann. de Chim. xxii. 186. 



10. Thenar d's Blue. — This blue is considered by M.Thenard, 

 as a combination of alumine and oxide of cobalt, and is prepared 

 in the following manner. Nitrate of cobalt prepared in the usual 

 way, from the ore of cobalt by torrefaction, digestion in nitric 

 acid, evaporation, and solution, is to be precipitated by a solution 

 of sub-phosphate of soda. The insoluble phosphate of cobalt is 

 to be well washed, and then collected together, whilst in the 

 gelatinous state, and mixed in the most perfect manner possible, 

 with eight times as much hydrate of alumina in the same state. 

 The mixture is spread on smooth plates, dried in a stove, when 

 hard and brittle reduced to powder, and heated in a covered 

 earthen crucible. After half an hour's ignition, it should be 

 taken from the fire, and should then be of the colour required. 

 The operation is always successful if the precautions be at- 

 tended to, and it is particularly important, that the gelatinous alu- 

 mina shall have been precipitated by an excess of ammonia, 

 and has been well washed with very pure water, until quite free 

 from impurity. 



The arseniate of cobalt may be employed in place of the 

 phosphate, but it requires twice as much alumina to be mixed 

 with li.— Diet. Tech.— Tech. Rep. iii. 340. 



11. On a Persulphate of Iron and Ammonia. — Dr. Forch- 

 hammer having prepared a solution of gold by means of nitric 

 acid and muriate of ammonia, and precipitated the gold by 

 proto-sulphate of iron, the clear solution was concentrated to 



