Intelligence and Miscellaneous Articles. 79 



ON THE PERIODIDE OF IRON. 

 To the Editors of the Philosophical Magazine and Journal, 

 Gentlkmen, 



Having noticed in our recent chemical works an account of a per- 

 iodide of iron, and the method adopted for its preparation being to 

 expose the protiodide in solution to the free action of air, I have pre- 

 sumed to offer an opinion, and I do apprehend that the change in this 

 case which takes place is a peroxidation of a part of the iron which 

 falls, and its equivalent of iodine is left free in the solution of the yet 

 unchanged protiodide of iron, and a portion remains thus unchanged 

 after a thin stratum has been exposed several weeks, which a solution 

 of potash will indicate by precipitating a protoxide of iron ; but there 

 is no periodide of iron in this solution, nor could I form a periodide 

 bv a persalt of iron and iodide of potassium, and I believe no such 

 compound to exist. 



Whilst upon this subject, it may be perhaps not uninteresting to 

 the medical part of your readers to give a short account of the prot- 

 iodide. It was first employed in medicine by Dr. A.T. Thomson, and 

 has since kept its character as a valuable tonic: the great inconvenience 

 arising from its tendency to decompose when dissolved in water, is 

 completely obviated by a coil of iron wire traversing the whole column 

 of the solution, which was suggested by me when it came into exten- 

 sive use as a therapeutic agent, and nearly three years' experience 

 proves it to answer most satisfactorily the object intended : it will 

 preserve it perfectly neutral even if the solution be fully exposed to 

 air and light ; it is true, in that case more peroxide is formed, but, 

 filter the solution when you will, it is perfectly colourless, and trans- 

 parent as distilled water : this is a very important point, and one which 

 the medical profession should be made fully acquainted with, being a 

 safe test for its neutrality and purity. Any colour, however slight the 

 tinge, shows the presence of some iodine in a free state, or some im- 

 purities derived probably from one of the materials employed to make 

 it 3 this no doubt has given rise to the difference of opinion as to its 

 action on the animal ceconomy. The colourless neutral compound 

 when diluted has an agreeable flavour, similar to that of a chalybeate 

 spring, whereas any free iodine gives a mawkish taste and is liable to 

 nauseate the stomach. 



I am, yours, &c,, 



P. Squire. 



227, Oxford Street, May 12, 1836. 



METEOROLOGICAL OBSERVATIONS FOR MAY 1836. 

 Chiswick — May 1, 2. Slightly clouded: stormy. 3. Cold and windy. 



4. Cold rain. S. Rain: cloudy and fine. 6. Light haze: fine. 7 — 10. Fine. 

 11 — 18. Veryfine. 19. Cold haze: fine. 20. Very fine: rain at night. 

 21, 22. Fine. 23. Rain : stormy. 24. Clear and cold. 25—28. Cold 

 and dry. 29 — 31. Fine. 



Boston. — May 1. Fine. 2. Stormy. 3. Stormy : rain p.m. 4. Rain. 



5. Stormy: rain early a.m.: rain p.m. 6, 7. Fine. 8 — 10. Cloudy. 

 11— 18. Fine. 19. Cloudy. 20. Fine : rain p.m. 21,22. p'ine. 

 SS.Stormy. 24, 25. Cloudy. 26— 30, Fine. 31. Cloudy. 



