Meteorological Observations. 319 



DOUBLE SULPHATE OF PROTOXIDE AND SESgUlOXIDE OP IRON. 

 BY M. J. A. POUMAREDE. 



When a mixture of two parts of protosulphate of iron and two 

 parts of persulphate of iron, theoretically neutral, is treated with five 

 or six parts of distilled water, it is found, after a contact of fifteen to 

 twenty minutes, that the mixture becomes considerably warm, ac- 

 quiring a temperature of 77° to 86° Fahr. above that of the ?urround- 

 ing air. In addition to this the two salts are found to dissolve en- 

 tirely, yielding a perfectly bright brown liquor, which becomes a 

 crystalline mass by proper evaporation. 



There are two remarkable facts to be noticed in the reaction above 

 described : first, the increased temperature of the mixture ; secondly, 

 the solution of two salts, of limited solubility, to an enormous extent 

 in a small quantity of water, and these are characteristics of chemical 

 action ; the new salt crystallizes in long slender crystals ; they have 

 a very pale green colour, a slightly styptic taste, and a very distinct 

 sweet after-taste. 



By long exposure to the air this salt is covered with subsulphate 

 of peroxide ; but the tendency to peroxidize appears to be less than 

 that of the protosalts of iron ; when heated it fuses readily, loses its 

 water of crystallization, afterwards the acid of the persulphate, and 

 at a still higher temperature it yields all the products obtained by 

 decomposing the protosulphate ; water dissolves it in all proportions. 



This salt was analysed by determining the increase of weight 

 which it acquired by conversion into persulphate. — Journ. de Pharm. 

 et de Ch., Juin 1844. 



METEOROLOGICAL OBSERVATIONS FOR AUGUST 1844. 



Chiswick. — August I. Cloudy: boisterous: clear. 2. Clear and very fine. 

 S. Showery : boisterous. 4. Dusky clouds : clear .nnd fine. 5. Cloudy and 

 fine: rain. 6. Boisterous: clear and fine. 7. Clear: heavy shower at noon: 

 clear and fine. 8,9. Fine. 10. Slight haze: fine. 11. Very fine: rain. 12. 

 Heavy rain. 13. Showery. 14. Rain: heavy squall : clear and fine at night. 

 15. Cloudy. 16. Very fine. 17. Densely overcast. 18, 19. Very fine. 20. 

 Overcast: fine. 21 — 25. Cloudy and fine. 26. Cloudy, 27. Cloudy and dry. 

 28. Clear, with hot sun. 29. Cloudless and hot. SO. Fine. 31. Hot and 

 dry. — Mean temperature of tlie month 2°'57 below the average. 



Boaton. — Aug. 1. Cloudy: rain early a.m. : rain a.m. 2. Fine. 3. Rain: 

 rain early A.M. : rain with thunder and lightning A.M. : rain P.M. 4. Cloudy. 5. 

 Fine: rain at night. 6. Cloudy. 7. Stormy : rain early a.m. : rain with thunder 

 and lightning A.M. 8. Windy : rain a.m. 9. Windy. 10. Fine. 11. Fine: 

 rain P.M. 12. Rain. 13. Fine. 14. Rain : rain early a.m. : rain a.m. and p.m. 

 15. Cloudy: rain early A.M. 16. Fine : rain p.m. 17. Cloud}'. 18 — 21. Fine. 

 22—24. Cloudy. 25. Fine. 26. Cloudy. 27—31. Fine. 



Sandwich Ma7)se, Oiknmj. — Aug. I. Cloudy: rain. 2. Bright: clear. 3. 

 Showers: drizzle. 4. Damp: drizzle. 5. Cloudy. 6. Cloudy: rain. 7. Showers: 

 cloudy. 8. Cloudy : showers. 9. Showers. 10 — 13. Bright : clear. 14. Bright: 

 clear: fine. 15. Clear: fine. 16. Bright : cloudy : fine. 17. Showers: rain. 



18. Bright: cloudy. 19. Bright: damp. 20. Showers. 21. Rain : drizzle. 

 22. Rain : damp. 23. Damp. 24. Damp : cloudy. 25. Bright : cloudy. 

 26. Drizzle : drops. 27. Drizzle : showers. 28. Bright : clear. 29. Clear. 

 30. Clear: warm. 31. Clear : cloudy : warm. 



Applegarth Manse, Dumfries-shire. — Aug. 1 — 3. Showers. 4. Fair. 5. Fine. 

 6,7. Heavy rain. 8. Rain a.m. : fair p.m. 9. A shower. 10. Fair a.m. : few 

 drops P.M. 11. Fair A.M. : rain p.m. 12. Fair. 13. Showery. 14. Showery: 

 thunder. 15. Fair. 16. Rain p.m. 17. Heavy showers. 18. Fair and clear. 



19. Heavy showers. 20. Fair. 21. Fair : a few drops. 22. Rain. 23. Heavy 

 shower P.M. 24. One shower. 25 — 31. Fair and fine. 



