102 Chronicles of Science. [Jan., 
Mr. Forbes has also analyzed some Welsh stream-gold from the 
river Mawddach, about eight miles above Dolgelly. The metal 
yielded 84:89 per cent. of gold, and 13:99 of silver. 
In the “Rowley Rag,” a well-known basaltic rock from the 
South Staffordshire coal-field, the same chemist has detected minute 
grains of a black mineral, which, on analysis, proved to be T%tano- 
Ferrite, or titanate of iron, having the followmg composition :— 
Titanic acid . ; F x 34°28 
Oxide of iron . : : 5 : 65:72 
100:00 
Mr. Forbes brings his paper to a conclusion by noticing a newly- 
discovered silver ore from the Foxdale mines in the Isle of Man. 
This ore, which contains 13 per cent. of silver, occurs in sufficient 
quantity to form an object of considerable commercial importance. 
The mineral is an argentiferous fahlerz, such as the Germans would 
call Weissgiltigerz, but which the author describes under the rarely 
used name of Polytelite. 
Among the recent reports on the advancement of French litera- 
ture and science, published under the direction of the Minister of 
Public Instruction, it comes within our province to notice only 
the “Report on the Progress of Mineralogy,’ drawn up by M. 
Delafosse.* By giving a réswmé of nearly all the mineralogical 
work which has been conducted in France within the last quarter 
of a century, the reporter shows that his countrymen, led by such 
men as Dufrénoy and Descloiseaux, have played a part in the 
advancement of our science by no means discreditable to the 
fatherland of Haity and De I’Isle. 
Those who love to speculate on the ultimate constitution of 
matter, and to study the recondite laws of crystallogeny, will find 
much to interest them in an essay on the “ Molecular Constitution 
and Growth of Crystals,” recently published by Dr. Adolph Knop, 
of the Polytechnic School of Carlsruhe.} 
It is well known that certain varieties of sandstone enjoy to a 
limited extent the curious property of flexibility. Such flexible 
sandstone—known to the mineralogist as Itacolumite—is usually 
found in association with the diamond, and, so far as our knowledge 
at present extends, appears to be restricted to the mining districts 
of Brazil and the Ural Mountains, to the neighbourhood of Delhi 
in India, and to the gold-bearing States of Georgia and North 
Carolina. As itacolumite always contains more or less disseminated 
tale or mica, its flexibility has usually been referred to the presence 
of these elastic scales. This opinion has, however, been lately 
* «Rapport sur les progres de la Minéralogie.’ Paris, 1867. 4to. pp. 97. 
+ ‘Molekularconstitution uud Wachsthum der Krystalle.’ Leipzig, 1867. 8yo. 
pp. 96. 48 woodcuts. 
