Mr. Graham's Account of the Formation of Alcoates. 331 



though the principle upon which they act has not been pro- 

 perly understood, and consequently they have never been 

 employed to the best advantage for this purpose. Dr. Mac- 

 culloch relates a very important case, where a superintendant 

 engaged in directing the cutting of wood in Africa, erected 

 thirty earthen furnaces on the spot where his men were em- 

 ployed, lighting them every day. Before this, he had always 

 from forty to forty-eight of his workmen sick ; when in a 

 short time they were reduced to twelve, then to four, and 

 finally to one. Napoleon adopted the same expedient very 

 largely, and with success, when his armies were occupied in 

 the very worst district of Italy*. Knowing the principle of 

 their operation, I should recommend them to be lighted at 

 sun-set, and to be allowed to burn until sun-rise, having a re- 

 gard to their position as pointed out in the foregoing remarks. 

 Where Jarge numbers of human beings are congregated to- 

 gether, as in armies, camps, &c, and where their situation at 

 night is too often determined by other circumstances than sa- 

 lubrity, the value of, these observations, with the knowledge of 

 the principles which should direct their application, cannot but 

 be very apparent. 



It will be easily seen, from what has already been said, that 

 fires as defences against malaria will be much more necessary 

 during the nocturnal period than at any other ; and even at 

 this season, when the wind is blowing strongly and the night is 

 overcast, they will not be so much required as when the air is 

 clear and still. — It is not my intention to speak here of those 

 various extraneous circumstances which render the body more 

 susceptible of injurious influences at night than during the 

 day, — such as bodily and mental exhaustion, sleep and dimi- 

 nished temperature ; nevertheless they are well worthy of our 

 serious regard, as cooperating powerfully with noxious mias- 

 mata in producing a state of disease. 



Malvern, July 1, 1828. WlLLIAM ADDISON. 



I^VI. An Account of the Formatio?i of Alcoates, Definite Com- 

 pounds of Salts and Alcohol analogous to the Hydrates. By 

 Thomas Graham, Esq. M.A. F.R.S.E. 



[Concluded from page 272.] 

 II. Alcoate of Nitrate of Magnesia. 

 FT is difficult to expel the whole of the w r ater with which ni- 

 ■*- trate of magnesia is combined, without driving off a por- 

 tion of the acid, and decomposing the salt. For this salt may 

 * Maccul loch's Essav, p. 286. 



2 U 2 be 



