schaller: cuprodescloizite I lit 



The values obtainable from this equation may be computed 

 more conveniently and with sufficient accuracy by an empirical 



equation of the form 



R-l = (0.975 -e) (logi O 0i-log,„0 2 ) constant. 



A table is given, of values of R for the stage efficiencies e =0.1, 



0.2 0.8, and for expansion from 350 lbs. /m 2 abs. down to 



various lower pressures. When (i? — 1) is plotted against the lower 

 pressure as abscissa, for a given value of e, the value of (R-l) for 

 expansion between any two pressures within the limits of the curve, 

 with this stage efficiency, is equal to the difference of the ordinates 

 of the curve at the two pressures. Hence if a set of curves be 

 plotted from the data given for the various stage efficiencies, 

 the reheat factor may, b}^ interpolation, be found very expedi- 

 tiously for the expansion of wet steam between any two pressures 

 and with any stage efficiency. The curve for e = 0.1 is given and 

 its use illustrated. 



A much more exact assumption regarding the distribution of 

 the isopiestics in the saturation field leads to a very complicated 

 expression for R, but the values computed in this way are sensibly 

 identical with those found by the simple graphical method de- 

 scribed above, which may therefore be regarded as sufficiently 

 exact for use in designing. 



MINERALOGY. — Cuprodesdoizite from California. Waldemar 

 T. Schaller, Geological Survey. 



Some samples of reported vanadium ore, sent to the Survey 

 by A. L. Lombard and J. F. Main, of the Dirigo Alining and Mill- 

 ing Company, of Lcs Angeles, California, proved to be coated 

 with a deposit of cuprodescloizite. The associated lead minerals 

 are cerusite and vanadinite from which the cuprodescloizite seems 

 to be derived. The locality is given as Camp Signal in San Ber- 

 nardino County, California. 



A qualitative chemical test showed the presence in quantity 

 of lead, copper, zinc, vanadium and a little water. A direct quan- 

 titative determination of the vanadium gave 21 per cent of 

 V 2 5 . 



