468 



SCIENCE 



[N. S. Vol. XXVII. No. 690 



Mr. C. K. Wead expressed his high admira- 

 tion for the ingenuity of the methods used by 

 the lectui'er, the monumental patience with 

 which the laborious experiments were carried 

 out, and the skill with which the data have 

 been discussed. 



The ordinary man, and even the architect, 

 generally assumes that sound-waves in a room 

 which is only a few wave-lengths long, can be 

 treated like light-waves ; but the ease is one of 

 diffraction rather than of rectilinear propaga- 

 tion and of reflection by the laws of optics. 



A merit of Professor Sabine's work is that 

 he has been able to make a sort of summation 

 of the complex phenomena in all parts of a 

 room. His immediate result — the reverbera- 

 tion, or the number of seconds the sound can 

 be heard after the wind is cut off from his 

 standard organ pipe — is not in itself of any 

 value; but like the percentage of carbon diox- 

 ide in the air, which was considered before the 

 days of bacteriology to gauge the impurity of 

 the air, this duration can be measured and it 

 gives information about quantities far more 

 important than itself. _ _, _- 



J. S. DiLLER, 



Recording Secretary 



THE GEOLOGICAL SOCIETY OF WASHINGTON 



At the 199th meeting of the society, held 

 at the Cosmos Club, on Wednesday evening, 

 January 22, the following papers were pre- 

 sented. 



Regular Program 

 Deposits of Residual Iron Ore in Cuha: A. C. 



Spencer. 



In Cuba a great part of the deep residual 

 soils are highly ferruginous and in many 

 localities so rich in iron as to constitute 

 usable ores of that metal. Three districts, 

 passing under the names Moa, Mayari and 

 Cubitas, were described in which very large 

 tonnages of such iron ore exist. 



Certain features, of the deposits are very 

 like those of the high level laterite of India, 

 especially the occurrence of a deep bed of 

 yellow clay next to the basement of solid rock 

 and the common gradation of the yellow clay 

 into red earthy material, containing pisoliths 

 and irregular concretions of brown iron oxide 



which are locally cemented into continuous 

 but porous layers. 



In one of the regions named the combined 

 thickness of these materials varies from a few 

 feet to more than fifty feet, and a large num- 

 ber of analyses have proved that both the 

 ochreous clays and the material lying above 

 them contain on the average about 46 per 

 cent, of iron when dried at 212° F., so that aU 

 of the residual material is to be considered 

 as ore. In its natural state the ore carries 

 above 40 per cent, of water of which about 

 13 per cent, is said to be combined. Alumina 

 is present in excess of the amount required for 

 combination with the silica and is doubtless 

 present in the form of hydrated oxide. Phos- 

 phorus is uniformly low, averaging less than 

 .02 per cent, and chromium is always present, 

 the average amount being somewhat less than 

 two per cent. 



The fact that chromium is characteristic of 

 the ore is regarded as definite proof that the 

 material has been derived from the serpentine 

 which constitutes the underlying rock in each 

 of the three fields. 



The absence of ' discrete particles from the 

 material is taken as an indication that no 

 part of it is transported, and as strongly sug- 

 gesting its accumulation in situ as the in- 

 soluble residuum of complete weathering and 

 decay of the serpentine. The topography of 

 the ore fields also favors the idea of a simple 

 residual origin, since in each case the deposits 

 constitute surficial mantles over extensive sur- 

 faces practically wanting in local relief. 

 Though now uplifted and even warped, these 

 surfaces are interpreted as the remnants of 

 ancient peneplains upon which the sort of 

 rock disintegration, favorable to deep residual 

 deposits, would naturally take place. The 

 geologic period during which this planation to 

 base-level occurred can not be fixed but, in the 

 mind of the speaker, is to be tentatively cor- 

 related with Lafayette and pre-Lafayette time. 



Systematic chemical work is demanded by 

 the whole problem of the genesis of these 

 ores, but the best promise of immediate re- 

 sults would seem to be offered by an investiga- 

 tion of the variations in the state of hydra- 



