128 Royal Society. 



by abundance of phosphate of magnesia, and the deficiency 

 of ammoniacal salts ; the fluid excrements (urine) have, on the 

 contrary, abundance of ammoniacal salts (from the decompo- 

 sition of urea) and are deficient in earthy salts; relations 

 which make it probable that the formation of such large cry- 

 stals in such quantities (they occur in thousands) was caused 

 by a reaction of the urine upon the solid excrements, where 

 the first gave the ammonia, the latter the phosphate of mag- 

 nesia. 



The locality where the crystals are found confirms this as- 

 sumption. The place where St. Nicholas's church is built 

 was occupied 800 years ago by the New Castle (Neue Burg), 

 which was burnt and destroyed with the whole city of Ham- 

 burg, in 1072, by Kruko, tyrant of the Wenden. Now it is 

 most probable that the ditch of the castle was used as a reser- 

 voir for rubbish and manure by the inhabitants of the new- 

 built city, who preferred trade, as more profitable, to agri- 

 culture. So by degrees the ditch was filled, and covered 

 partly with houses, and a small part of it formed till a late 

 period an open dung-pit, which was emptied from time to 

 time. The crystals are found principally below the dung-pit, 

 and appear to be formed by the infiltration of urine through 

 a soil consisting of vegetable matters. 



The crystals forming a mineral which has never yet been 

 described, are named Struvite, in honour of the minister Von 

 Struve, well-known to mineralogists, and highly meritorious 

 from the great interest he takes in the advancement of science 

 in the town of Hamburg. 



XXV. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



[Continued from p. 54.] 



April 2, " f\N the Effects produced by Poisonous Fish on the 

 1846. ^ Human Frame." By Sir William Burnett, M.D., 

 K.C.H., Vice-President of the Royal Society. 



The author communicates a report which he lately received from 

 Mr. Jameson, the surgeon of the flag ship at the Cape of Good 

 Hope, of the rapidly fatal consequences ensuing from eating small 

 portions of the liver of a fish, known at the Cape by the name of 

 the Bladder or Toad fish, the Aptodactylus punctatus, or Tetrodon 

 of Cuvier. The symptoms were chiefly pain and burning sensation 

 at the epigastrium, constriction and spasm of the fauces and mus- 

 cles of deglutition, rigidity of the tendons, coma, paralysis and con- 

 vulsions, following one another in quick succession, and terminating 

 in death within twenty minutes after the poisonous food had been 



