^Si Intelligence and Miscellaneous Articles. 



quantity obtained difft-rs but little from that indicated by theory ; it is, 

 therefore, of little consequence which of the processes is adopted in 

 preparing small quantities of the iodide; the case is, however, different 

 when considerable quantities of the ingredients are employed, as 

 in this case the differences are too considerable to be neglected. 



The author thinking that some experiments which he has made 

 on the subject would not be uninteresting, has published them ; and 

 in every case such a quantity of iodine or iodide was employed as 

 ought to yield, by theory, 18"20 grammes of iodide of lead. 



Process by Iodide of Potassium. — This process is that originally 

 employed ; it consists in decomposing iodide of potassium by a salt 

 of lead. The Codex prescribes the neutral acetate, but this salt has 

 been generally abandoned since it was discovered by M. Depaire 

 and Felix Boudet, that nearly one-tenth of the iodide of lead was 

 dissolved by the acetate of potash formed ; 13"10 grammes of iodide 

 of potassium containing 10 grammes of iodine were treated with 

 neutral acetate of lead ; the weight of the iodide precipitated was 

 15-70 to 15-80 grammes. 



To avoid the loss occasioned by the use of acetate of lead, M. 

 Boudet proposed to substitute the nitrate for it ; by this process M. 

 Huraut obtained with 13' 10 grammes of iodide of potassium from 

 17-50 to 17-55 of iodide of lead. 



Iodide of lead prepared with iodide of potassium is of a fine lemon- 

 yellow colour, and entirely soluble in boiling water. 



Process by Iodide of Sodium. — Ten grammes of iodine converted 

 into this salt gave with acetate of lead 15-90 to 16" 10 of iodide, and 

 with the nitrate 16-85 to 16-95. It resembled that obtained with 

 iodide of potassium perfectly. 



Process by Iodide of Calcium. — A quantity of this containing 10 

 grammes of iodine, gave 17-60 to 17*70 of iodide of lead, of a fine 

 orange-yellow colour. In one experiment, so performed as to pro- 

 duce a crystalline iodide, the product was remarkably brilliant ; with 

 acetate of lead 17*25 to 17 '40 of iodide were produced, also of a fine 

 orange- yellow colour. 



Process by Iodide of Iron. — Ten grammes of iodine converted into 

 iodide of iron and treated with neutral acetate of lead, gave 16-70 

 to 16-75 grammes of iodide of lead; with nitrate the products were 

 17-50 grammes; they were orange-yellow, and totally soluble in 

 boiling water in both cases. 



Process by Iodide of Zinc. — This salt is now perhaps that most 

 commonly employed in preparing iodide of lead ; the preference 

 given to it arises from the facility with which it is prepared, its 

 great solubility and unalterability in the air; 10 grammes of iodine 

 converted into this salt gave with acetate of lead 17-05 to 17*15 

 grammes of product, and with the nitrate 17-40 to 17-45. The 

 colour is palish orange-yellow. 



Process by the double Iodide of Potassium and Lead. — This is a 

 complicated plan proposed by M. Thevenot; the author compared 

 the product with that afforded by the above-described processes ; 

 the comparison was in favour of the latter. M. Huraut concludes 

 from the above-described experiments, that in the preparation of 



