Letter from M, A. Htimloldt, &c. 365 



expended In producing the effects we observe in the combus^ 

 tion of gunpowder. 



The residuum of fired gunpowder Mr. Howard thinks to 

 be an alkaline sulphuret mixed with carbonat and sulphat of 

 potash. But by several trials I have long since made, 1 am 

 induced to form the same opinion, as to the qualities of this 

 residuum, as Mr. Cruickshank : the quantity I have not had 

 an opportunity of ascertaining. Mr. Cruickshank says : 

 *' This residuum is very deliquescent, and when exposed to 

 the air absorbs nioisture sufficient to dissolve a part of the 

 alkali ; in consequence, the charcoal becomes exposed, and 

 the whole assumes a dark or black colour : that this residuum 

 is potash united with a small quantity of sulphuret of potash 

 and unconsumed charcoal: and that 100 grains of gunpowder 

 yield 53 grains, of which three are charcoal." 



XLV. Letter from M. A. Humboldt to C. Delambre, 



Member of the French National Institute, 

 _^^ New Barcelona, Nov. 24, 1800. 



i-JURING my stay in South America I dispatched several 

 letters to you and Lalande. I know you are interested in my 

 fate, and I never let slip an opportunity of writing to you, 

 though I have scarcely any hopes of my letters reaching the 

 place of their destination. I am now on the point of setting 

 out for the Havannah and Mexico, after having performed 

 a tour of thirteen hundred nautical leagues in this part of the 

 New World, situated between Popayan, Quito, and Cayenne. 

 I have slept for three months in the open air, in the woods, 

 surrounded by tigers and hideous serpents, or on plains co- 

 vered with crocodiles. Bananas, rice, and manioc, have 

 been our sole nourishment; for all provisions soon become 

 putrid in this damp and scorching country. 



How grand and majestic is nature among these mountains.! 

 From Baraquan and Uruana, which unknown nations have 

 covered with hieroglyphics, as far as the volcano of Duida, 

 at the distance of sixty leagues from the small lake of Dorado, 

 the elevation of which I have found to be 2176 metres, there 

 is only one cordillera of granite, that descends from Quito, 



and 



