134 Scientific Intelligence. 



The work of translation has been well done, the corresponding 

 technical terras in English having been carefully considered, 

 while the phraseology is idiomatic and free from foreign con- 

 structions. It is handsomely printed and bound and is a work 

 that should be in every technical library and in the hands of all 

 who are interested in ore-deposits. l. v. p. 



12. Practical Instruction in the Search for, and the Determin- 

 ation of, the Useful Minerals, including the Rare Ores ; by 

 Alexander McLeod. Pp. ix, 114. New York (John Wiley & 

 Sons). — It is not often that so practical a study as that of pros- 

 pecting for useful minerals is discussed by one who has had 

 many years' experience in active work. That is the case, however, 

 with the little volume in hand ; and the directions given, and the 

 tables for the determination of mineral species and other matter, 

 should prove useful to those needing such help. 



13. The Origin of Thanmasite ; by Frederick I. Allen. 

 (Communication to the Editor.) — This rare mineral, with the 

 remarkable composition represented by the formula CaSi0 3 . 

 CaC0 3 .CaS0 4 .15H 2 0, was found at Burger's Quarry, West Pater- 

 son, N". J., and was identified and studied by Penfield and Pratt 

 in 1896.* Recently I have obtained from this same quarry hand- 

 some specimens of pale blue, transparent anhydrite, CaS0 4 , asso- 

 ciated with amethystine quartz. The crystals are simple and in 

 fan-shaped aggregates. They are lath-shaped, much compressed 

 parallel to c (001) and greatly extended parallel to a (100) ; the 

 forms observed are the three pinacoids, a, b, c, (100), (010), (001). 

 The composition-plane of the fan-shaped aggregates is c. . 



Among the specimens of anhydrite were a number that were 

 partially changed to thaumasite, and these showed every grada- 

 tion of change from the blue, transparent mineral to the white, 

 opaque product. There is no doubt, therefore, that the thaumasite 

 is an alteration product of anhydrite. The thaumasite has in 

 many cases disappeared from the places of its formation, leaving 

 cavities in the quartz in the form of the original anhydrite crys- 

 tals. Specimens showing these rectangular cavities have been 

 collected in large numbers, but it has not been known heretofore 

 what mineral these pseudomorphs represented. Dr. W. M. Brad- 

 ley of the Sheffield Scientific School has kindly given me his 

 assistance in confirming the identity of the minerals. 



III. Miscellaneous Scientific Intelligence. 



1. National Academy of Sciences. — The autumn meeting of 

 the National Academy was held in Chicago on Dec. 7, 8, 9. The 

 sessions were carried on in the buildings of the University of 

 Chicago and the support and hospitality extended by the Presi- 

 dent and the members of the Scientific staif of the University 

 contributed very largely to the success of the meeting. Two 

 public lectures were delivered by Professor W. W. Campbell, 



* This Journal [4], i, 229. 



