Record. xli 



October 19, 1903. 



President Eliot iu the chair, thirty-five persons present. 

 This was the first meeting held in the new Academy Building, 

 3817 Olive street. 



The Council reported that the following names had been 

 dropped from the membership roll: J. H. Boogher, M. F. 

 Engman, E. Grebe, A. Habermaas, A. A. Henske, J. Maser- 

 ang, Jr., C. H. Stone, O. Sutter, and O. M. Wood; that the 

 resignation of Professor A. S. Chessin had been accepted ; 

 and that the Zoological Institute, Cagliari, had been added to 

 the exchange list. 



Professor F. E. Nipher gave an abstract of the results of 

 his paper on the " Law of Nebular Contraction," which has 

 just been published in the Transactions. He also remarked 

 that the molecular conditions iu nebulae of different gases 

 were being examined, and some very interesting results are 

 at once evident. If a series of nebulae of various gases have 

 the same mass internal to the same radius, the average m.ole- 

 cular velocities would be the same for all gases. The velocity 

 which would enable a molecule to escape from the nebula is 

 2.71 times the average molecular velocity, and this ratio is 

 constant for all parts of the nebula. If the entire solar 

 system formed the core of such a nebula, and the mass of 

 the solar system extended to Neptune's orbit, the density at 

 that distance from the center of the nucleus would be less than 

 that in a Crookes tube. This opens up some very interesting 

 questions concerning the history of such a mass. It would 

 appear that such a gravitating mass would lose some heat by 

 the escape of the more rapidly moving molecules, as well as 

 by radiation. 



Professor E. H. Reiser read a paper on a method of de- 

 termining the amount of lime in cements. He finds that 

 this can be done by determining the amount of water ab- 

 sorbed. B}^ measuring this absorption in samples containing 

 known amounts, the precautions to be taken in manipulation 

 have been found. The determination only requires about 

 twentv minutes. 



