Septembek 6, 1907] 



SCIENCE 



307 



prior to the effusion, but at moderate depths; 

 while the formation of the microlites of leu- 

 cite took place during the effusion. The 

 lapilli -which covered Ottajano show very de- 

 cided chemical differences from these, espe- 

 cially in their higher magnesia and lime and 

 lower alkalies. 



In Chapter III. are described the fragments 

 of an earlier date brought up by the last 

 eruption, including lavas, tuffs, intrusive rocks 

 and metamorphosed limestones. In Chapter 

 IV. the effects of autopneumatolysis and meta- 

 morphism on these fragments at Vesuvius, 

 and in Chapter V. the similar phenomena at 

 the volcanoes of the Auvergne, Santorini and 

 Martinique are discussed. Many interesting 

 details are here given, which are too numerous 

 for review and for which the original mono- 

 graph must be consulted. 



The final Chapter VI. is devoted to a gen- 

 eral discussion and description of the eruptive 

 rocks of Somma and Vesuvius, and is to the 

 petrographer the one of greatest interest and 

 value. A large number of diverse types are 

 described, accompanied by numerous, good 

 analyses by Pisani. Lacroix shows that the 

 variation in composition, both mineralogical 

 and chemical, of the Vesuvian lavas is far 

 greater than has hitherto been thought. In 

 the terms of the prevalent classifications the 

 rocks described are leucite-phonolite, leucite- 

 tephrite, trachyte, phonolite, sanidinite, micro- 

 syenite, sommaite (leucite-monzonite) and 

 monzonite, with corresponding chemical dif- 

 ferences, the silica, for instance, varying from 

 47.31 to 58.61 per cent. In terms of the 

 quantitative classification, which, it is of in- 

 terest to observe, is employed throughout the 

 work in connection with that commonly in 

 use, the subrangs represented are beemerose, 

 procenose (I. 6. 2. 3), miaskose, ciminose, sho- 

 shonose, borolanose, braccianose, vesuvose, 

 shonkinose, ottajanose (III. 6. 3. 2), ourose, 

 and an unnamed one (III. 8. 2. 3). It may 

 be noted, however, that, while the mineralog- 

 ical and chemical complexity of the mass is 

 thus evident, yet that the predominant rocks 

 are leucite-tephrites, belonging to the sub- 

 rangs borolanose and braccianose of the quan- 



titative classification, the non-leucitic rocks 

 and those belonging to the persalane and sal- 

 femane classes being present in comparatively 

 small amounts. From the analytical data 

 presented Lacroix considers that the average 

 magma of Somma- Vesuvius belongs to boro- 

 lanose (II. 6. 2. 3), the Vesuvian lavas being 

 mostly dopotassic, while the lavas and tuffs 

 of Somma are for the most part sodipotassie. 

 This introduction of the materials of Somma 

 into the calculation explains the divergence 

 from the position of braccianose (II. 7. 2. 2) 

 previously assigned by the reviewer to the 

 Vesuvian magma. In this final chapter is 

 also included a brief discussion of the forma- 

 tion of leucite, the author laying special stress 

 on the physical conditions, while the reviewer 

 has recently (in the Journal of Geology) dis- 

 cussed the question chiefly from the chemical 

 side, the results of both being in harmony 

 with each other. 



Ten plates of excellent phototypes, illustra- 

 ting, the microscopic and megascopic modes 

 and textures of the rocks, close the volume, 

 which is a most important contribution to our 

 knowledge of Italian volcanoes, and is an il- 

 luminating example of a modern petrographic 

 monograph. 



Henry S. Washington 



The Royal Society: some account of the 

 " Classified Papers " in the Archives; with 

 an Index of Authors. Compiled by A. H. 

 Church, D.Sc, F.R.S, Oxford; printed for 

 the author. 1907. Pp. 38. Eoyal 8vo. 

 Professor A. H. Church, the distin- 

 guished chemist, student of colors, water, 

 gems, and critical author, has published a most 

 exhaustive and interesting account of the 

 " Classified Papers " in the archives of the 

 Royal Society of England. These papers are 

 collected in thirty-nine guard-books, which 

 were made up in 1740 or 1741; a few of the 

 papers were printed, but the greater part are 

 in manuscript. Professor Church gives a 

 comprehensive, clear and incisive account of 

 the formation and character of the early his- 

 tory of that learned institution, known for the 

 past two and a half centuries as " The Eoyal 



