302 Prof.Berzeliuson [Apbil, 



I. Researches on the Relation of the Iron to the other Bases in the 

 ferruginous Hydrocyanates. 



(A.) Salt with Base of Potash. 



The salt was purified in the following manner : Crystals that 

 had effloresced were heated in close vessels until the mass 

 entered into fusion. This was then dissolved in water, and 

 twice ciystallized. The solution was not rendered turbid by 

 hydrocyanate of barytes, and the salt had alight, but pure lemon- 

 yellow colour. It was pulverized, and left exposed to the air 

 for two days without losing any weight. Exposed afterwards 

 to the temperature of 140° Fahr. it effloresced, and lost between 

 0*129 and 0-124 of its weight: these numbers are the two 

 extremes of seven experiments. It lost nothing further, at a 

 temperature higher than that of boihng water. 



I mixed 30*88 grs. of the salt thus dried, with sulphuric acid 

 in a platina crucible ; the mass heated, but without any efferves- 

 cence, and no smell of hydrocyanic acid was perceptible. 

 Heated on the sand bath, it sustained no change, and it was not, 

 until it had been exposed to the flame of a spirit-lamp, that it 

 began to be decomposed. A quantity of gas was then disen- 

 gaged, which had not only the smell of sulphurous acid, but also 

 that of the hydrocyanic. The heat was continued until the excess of 

 sulphuric acid was driven off, and water was poured on the mass 

 when cold. The sulphate of iron dissolved slowly; it was 

 necessary to add water, slightly acidulated with muriatic acid, 

 to obtain a complete solution. 



The clear liquor was precipitated by caustic ammonia added 

 in excess. The oxide of iron w^as thrown on a filter, and washed 

 with a large quantity of water. The salt remaining in the solu- 

 tion and washings was evaporated to dryness, and heated red in 

 a platina crucible. It is hardly possible to prevent a portion of 

 the ammonia from being volatilized at the commencement of this 

 operation, and consequently an acidulous sulphate of potash 

 remains, which it is difficult to deprive entirely of its excess of 

 acid. To get rid of this excess, I introduce a small piece of 

 carbonate of ammonia, by a platina spoon, into the crucible, while 

 the mass is still red hot. 1 then put on the cover to check the 

 escape of the ammoniacal gas. The sulphuric acid almost 

 instantly evaporates in the alkaline atmosphere, and the salt 

 becomes neutral. In this manner I obtained in three separate 

 experiments 29*11, 29*17, 29*49 grs. of sulphate of potash, equi- 

 valent to 61*09 hundredth of the weight of^ the anhydrous ferru- 

 ginous prussiate. The oxide of iron weighed, in the different 

 experiments, between 6*17 and 6*64 grs. Dr. Thomson's asser- 

 tion, that a portion of the iron is volatilized with the hydrocyanic 

 acid, induced me to try another method of separating it from 

 this metal. I dissolved the ferruginous prussiate of potash ia 

 water, added hydrate of deutpxide of mercury to the solutioiu 



