March, 1847.] 191 



were to be found, the Cicada had nearly disappeared, while they 

 abounded where the moles had not been. Many larvse of the 

 Scarites Icevigatus were found, no doubt doing their full share 

 to rid us of so great an evil." 



Dr. Leidy, from the Curators, read a letter from Dr. J. K. 

 Mitchell, Chairman of a committee of the delegation from the 

 city and county of Philadelphia to the National Medical 

 Convention, returning acknowledgments to the Academy for 

 the offer of its Hall for the use of the Convention, and accept- 

 ing the same. 



The Corresponding Secretary read a letter from Judge 

 Tremper, dated Dresden, N. Y., March 8, 1847, containing 

 some Meteorological observations. 



Professor Johnson communicated some observations and experi- 

 ments on the dust of anthracite furnace flues. Having several 

 years since ascertained the presence of large quantities of salts of 

 ammonia, both sulphates and chlorides, in flues aud stove pipes 

 where anthracite is consumed, he had recentry directed attention 

 to this as a source from which a moderate supply of these salts 

 for the uses of horticulture may readily be obtained. It was 

 therefore deemed worthy of a trial to ascertain in what proportion 

 the salts soluble in water might occur in the dust of a flue, such 

 as ordinary practice in domestic use would afford. For this pur- 

 pose, oue pound of the dry dust was heated with successive por- 

 tions of distilled water until the liquid ceased to be coloured, or to 

 give a saline residuum on complete evaporation. The liquid 

 was of a dark brown colour, and on analysis afforded. 



Sulphate of lime, ..... 12.3 grains 



Sulphate of Ammonia, .... 285.5 

 Chlor-hydrate of Ammonia with undetermined 



compound tarry matter, - - 20.4 



Total in 1 pound - 478.8 grains, or 



6.84 per cent., or including the losses incident to the several steps 

 of analysis, may be taken at 7 per cent. 



