188G.] NEW YORK ACADEMY OF SCIENCES. 213- 



that the theory may have the advantage of both courses of rea- 

 soning. 



My reason for using the term "mitigated virus," instead of 

 ''attenuated virus/' most commonly used, is that mitigation is 

 as nearly as possible the idea in the French word (attenue) while 

 our own word attenuation conveys in ordinary parlance little of 

 the conception of a modification into less severe forms. 



April 5, 18S6. 

 Regular Business Meeting. 

 The President, Dr. J. S. Newberry, in the chair. 

 Seventeen persons present. 

 The following persons were elected Resident Members : 



Mr. John S. Brownne, 

 Mr. David S. Banks, 

 Mr. Lucius C. Ashley, 

 Mr. Joseph M. Knap. 

 A paper by Mr. George F. Kunz was read by title : 

 notes on some minerals from the west. 

 1. CeJestite from Lampasas Co., Texas. 



Some magnificent celestite in perfect blue crystals has been 

 found recently in a buff-colored limestone, associated with white 

 calcite crystals, in a railroad cutting in Lampasas Co., Texas. 

 They are now in the collection of Mr. Clarence S. Bement. 

 One crystal measures eight inches in length. It is of a fine sky- 

 blue color, and has a high polish on the faces of the crystal. 

 The faces measure 20x13x10 centimetres. Some smaller very 

 sharply defined crystals were also found here. 



2. TojKiz and Sjjessariite from Nathrop, Chaffee Co., Colorado. 



Beautiful brilliant specimens of topaz crystals, with single and 

 double terminations, measuring from five to twenty-five mm. in 

 length, have been lately obtained from the above locality. They 

 occurred in cavities of rhyolite; and with them were beautiful 

 crystals of spessartite, measuring in length from one to six mm. 



The spessartite (manganese alumina garnet) is of a translucent 

 rich blood-red color, and its faces are remarkably brilliant, the- 

 planes observed being 2-2 and i. In the topaz the faces observed. 



are 0, I, i-2, 2, 2-i, 13, i-"i. 



