Meteorological Observations. 319 



condensation ; and this is the cause which occasions the decrepitation 

 both by heat and solution in water. 



M. Dumas found that the gas extricated from this variety of salt, 

 when mixed with oxygen gas, detonated like hydrogen ; nevertheless 

 he supposed carbon to exist in it. He had not a sufficient quantity 

 of the salt to examine more minutely the gas condensed in these 

 crystals. 



M. H. Rose received from Professor Zeuschner of Krakaut, a con- 

 siderable quantity of the detonating salt, and he has been enabled 

 to repeat and verify the experiments of M. Dumas. The different 

 portions of salt did not all give the same quantity of gas when dis- 

 solved in water. The maximum, as stated by M. Dumas, amounted 

 to about half the volume of the salt. 



The gas, when burnt with oxygen, gave nearly the same compo- 

 sition as pond gas (C H 4 ). This product is probably so condensed 

 as to exist as a liquid or solid in the interior of the salt, and resumes 

 the state of an elastic fluid at common pressures. 



The property which this salt possesses ought in future to direct 

 the attention to a great number of minerals which occur in nature, 

 and which decrepitate in the fire without our being able to attri- 

 bute it to the disengagement of moisture. It may be that the cause 

 of the decrepitation is the disengagement of a gas condensed in the 

 mineral. Ann. de Chim. et de Phys., Mars, 1840. 



METEOROLOGICAL OBSERVATIONS FOR AUG. 1840. 



Chiswick. Aug. 1, 2. Very fine. 3 9. Hot and dry. 10. Very fine. 11. 

 Showery. 12. Cloudy: rain. 13. Cloudy. 14. Rain. 15. Very fine : show- 

 ery. 16. Fine. 17. Boisterous with heavy rain. 18. Cloudy. 19. Heavy 

 rain: cloudy and fine. 20. Fine. 21. Foggy: very fine. 22. Foggy. 23 

 26. Very fine. 27. Foggy: fine. 28. Slight fog : rain. 29. Foggy. 30,31. 

 Cloudy and fine. The mean temperature of the month was nearly 2 above the 

 average. 



Boston. Aug. 1 3. Fine. 4. Cloudy. 5 10. Fine. 11. Rain. 12, 13. 

 Fine. 14. Cloudy. 15. Stormy : rain P.M. 16. Fine. 17. Stormy : rain early 

 A.M.: rain with thunder and lightning P.M. 18. Stormy. 19, 20. Cloudy. 

 21. Fine: quarter past three P.M. thermometer 80. 22. Cloudy: rain P.M.: 

 lightning at night. 23, 24. Fine. 25. Fine : rain P.M. 26, 27. Cloudy. 28. 

 Fine. 29. Cloudy. 30. Fine: rain P.M. 31. Cloudy: rain A.M. 



N.B. The warmest August since 1826. 



Applegarth Manse, Dumfries-shire. Aug. 1,2. Very fine. 3. Mild: show- 

 ery A.M. 4. Fine. 5. Sultry. 6. Sultry : heat oppressive. 7 9. Sultry. 10. 

 Wet and boisterous P.M. 11. Showery. 12 14. Occasional showers. 15. Fair 

 throughout. 16. Much rain P.M. 17. Heavy rain: thunder: high flood. 18. 

 Fine drying day. 19. Fine, with one slight shower. 20. Drizzling all day. 

 21. Fine : rain P.M. 22, 23. Fine and fair all day. 24, 25. Showery. 26. Fair 

 all day and clear sky. 27. Wet P.M. 28. Fair all day. 29. Drizzling all day. 

 30. Fine and fair all day. 31. Remarkably fine harvest day. 



Sun shone out 27 days. Rain fell 15 days. Thunder 1 day. 



Wind north-west 5 days. East-south-east 1 day. South-east 4 \ days. South 

 7 days. South-south-west 4 days. South-west 8 days. Variable 1 day. 



Calm 1 2 days. Moderate 1 1 days. Brisk 5 days. Boisterous 3 days. 



Mean temperature of the month 57 0> 60 



Mean temperature of August, 1839. 55 '70 



Mean temperature of spring water 52-33 



