360 On the Sulphates of Barium and Strontium. [May, 



ceeding, is to put a particle into a drop of marine acid on a plate 

 of glass, and to let this solution crystallize spontaneously. The 

 crystals of chloride of barium in rectangular eight-sided plates 

 are immediately distinguishable from the fibrous crystals of chlo- 

 ride of strontium. 



I have not repeated the process above quoted ; but if sulphate 

 of strontium did possess the solubility in water there implied, 

 this quality presented a ready method by which mineralogists 

 would be enabled to distinguish it from sulphate of barium. On 

 trial I did not find water, or solution of sulphate of soda, in which 

 sulphate of strontian had long lain, produce the least cloud on 

 the addition of what is called subcarbonate of soda. 



The means I have long employed to distinguish the two sulphates 

 apart was to fuse with carbonate of soda, wash, dissolve in marine 

 acid, &c. ; but this process requires more time and trouble than 

 is always willingly bestowed, and may even present difficulties 

 to a person not familiarized with manipulations on very small 

 quantities. 



A few months ago a method occurred to me divested of these 

 objections. The mineral in fine powder is blended with chloride 

 of barium, and the mixture fused. The mass is put into spirit 

 of wine, whose flame is coloured red if the mineral was sulphate 

 of strontium. The red colour of the flame is more apparent 

 when the spirit is made to boil while burning, by holding the 

 platina spoon containing it over the lamp. 



Article IX. 



Observations on the Temperature, and general State of the Wea- 

 ther, on the Coast of Africa from the River Sierra Leone 

 (8° 30' N) to the Equator, but principally in the Gulph of 

 Guinea from Lat. 5° N. to the latter. By Capt. B. Marwood 

 Kelly, Royal Navy, late of his Majesty's Ship Pheasant. 



(To the Editor of the Annals of Philosophy.) 

 SIR, Jprili, 1823. 



From local peculiarities in the state of the weather on these 

 parts of the coast, it is usual to divide the year into seasons of a 

 denomination different from other parts of the globe ; in place of 

 spring, summer, autumn, and winter, they are here called the 

 tornado,* rainy, foggy, second or after rains, and fine seasons. 



* These violent convulsions in the atmosphere so terrific to sailors, and which would 

 be no less so to landsmen, if the state of cultivation was so far advanced, as to expose the 

 husbandman's labour to the ravages of these dreadful tempests, first shows itself on the 

 eastern quarter of the horizon by a deep black cloud heavily charged with electric fluid. 

 This cloud continues increasing in size, sometimes for an hour or two before it is put in 

 motion, and constantly emitting vivid flashes of lightning, accompanied by heavy and 



