2-0O LEAD. 



time to the surface of the body. " Even those places which are 

 near lead mines, are by no means healthy, though they are not 

 exposed to any of the fumes arising from the furnaces ; and it has 

 also been proved that people sitting in a room adjoining one that 

 has recently been oil- painted, are often affected with the usual 

 symptoms which lead produces when it has been taken into the 

 system, although they have not come directly in contact with it, 

 or any of its preparations. These facts seem to prove the accuracy 

 of the opinion, that a poisonous emanation arises from lead, or its 

 compounds, though we are totally ignorant in what it consists. 

 The most probable opinion is, that the lead or its compounds exist 

 in a state of minute division in the atmosphere, but are not held 

 in solution by any chemical agency. Lead itself is perfectly inso- 

 ble in water, but is soon oxidated and converted into a carbonate 

 by aerated water, (water containing free carbonic acid) ; in this 

 state, however, it is likewise insoluble in water, but is often me- 

 chanically suspended while in a state of minute division,* and is in 

 this manner introduced into the system. The carbonate has been 

 detected in water conveyed through leaden pipes for culinary pur- 

 poses, and in a ship where the water was kept in leaden vessels, all 

 the crew were soon affected with cholic. These circumstances 

 shew the impropriety of allowing water to stand for any length of 

 time in leaden cisterns, especially if they be exposed to air ; but if 

 the water contain any acidulous substance, the oxidation and solu- 

 tion, or diffusion of the lead in the water, will proceed much more 

 rapidly ; thus, vinegar oxidates and dissolves lead, forming an 

 acetate of lead, which is a soluble salt, and it is owing to its pre- 

 sence that wines act so readily on this metal. Any saline impreg- 

 nation also seems to favour its oxidation."! 



The effects of the preparations of lead on the animal economy 

 vary with the rapidity with which it enters the system. In large 

 doses the soluble salts of lead act as powerful irritant poisons, 

 causing inflammation of the stomach and alimentary canal. When 

 introduced slowly into the system, the intestines are first affected, 

 obstinate constipation from diminished action takes place, accom- 



* Brando's Journal, vol. xiv. p 240. 

 f ltcid's Academical Examinations , vol. ii. p. 39. 



