316 On Vaccination. 



First Indication of tlie Mineralogical Inquiries necessary to 

 he made as to the Existence of Potash. 

 In an essay upon the art of making saltpetre, which I 

 presented to the National Institute several years ago, I ex- 

 plained the origin of what is called natural soda, and I took 

 that occasion to inquire rvhat became of the potash corifined 

 in the bowels of the earth. About a year afterwards M. Kiap- 

 roth discovered it in several volcanic productions; and his 

 discovery was soon confirmed by M. Vauquelin. It is pe- 

 culiarly gratifvina; to me to have suggested the idea of these 

 useful researches, 



Probable Origin of Nat rum. 



I am strongly inclined to think that the natrum of the 

 lakes in Egypt and other places owes its origin to the de- 

 composition of the muriate of soda by potash, which is one 

 of the products of the disorganization of vegetables; for the 

 shores of the six lakes of Egypt, and the adjacent soils, are 

 covered with jonquils and roses, which must annually fur- 

 nish plenty of potash. It would be easy to verify this ex- 

 planation by experiments, w-hich promise more success than 

 those which have been made with other views. To con- 

 clude : the explanation which I thus gave, previous to the 

 late memorable trjivels of several of our learned men in 

 Egypt, before it be confirmed, would require us to prove 

 the coexistence of the muriate of potash along with the 

 other salts, in the lakes of natrum and in the waters of the 

 Nile 



XLVI. Report of the Royal College of Physicians of London 

 on Vacchiatinn. Printed by Order of the House of Com- 

 mons, dated St h July I807. 



-Lhk Royal College of Physicians of London, having re- 

 ceived his majesty's commands, in compliance with an ad- 

 dress from the house of commons " to inquire into the state 

 of vaccine inoculation in the united kingdom, to report their 



opinion 



I 



