184 Scientific Intelligence. 



Sulphuric acid decomposes it readily, even at the ordinary temperature 

 of our atmosphere ; it dissolves the alumina, and leaves the silica in a 

 gelatinous state, which is then soluble in alkalies. It was thus found by 

 M. Berthier to contain 



Silica, 0.395 



Alumina, 0.340 



Water, 0.265 



It does not contain either phosphoric or fluoric acid, lime, magnesia, 

 glucina, or oxide of copper; but it contains a small quantity of iron, which, 

 together with the bluish-colour of the mineral, makes M. Berthier sup- 

 pose a little phosphate of iron to be the cause of this colour. Dried in a 

 stove and then analyzed, it gave only 16 per cent, of water. It is difficult 

 to say how much water should be considered as being chemically combin- 

 ed, and how much only adherent by capillary attraction. — (Annates de 

 Chimie et de Physique, torn, xxxii. p. 332. J 



14. Artificial cold produced by mixing metals. — M. Dobereiner dissolved 

 207 gr. of lead, 118 gr. of tin, and 284 gr. of bismuth in 1617 gr. of mer- 

 cury, at a temperature of 64.5 degrees of Fahrenheit. The mixture im- 

 mediately fell to 14° Fahr. — (Annates de Chimie et de Physique, torn, xxxii 

 p. 334,. J 



ZOOLOGY. 



15. Mr Audubon's Ornithology of the United States of America,-— The 

 Ornithology of the United States of America, from drawings by Mr 

 John James Audubon, made during a residence of twenty-five years in 

 those countries, and now on view at the Rooms of the Royal Institution 

 here, is, we understand, about to be published. These drawings exceed 

 400 in number, amongst which upwards of eighty are undescribed birds; 

 and as the projected work will appear in parts, at moderate intervals, he 

 has promised to give one nondescript specimen in each fasciculus. The 

 book will consist of three volumes, double-elephant folio, coloured like the 

 author's beautiful drawings, and in every instance the engravings will be 

 the natural size of the birds, or, in other words, of the same dimensions as 

 the drawings themselves. We have seen two of the engravings at the 

 Royal Institution, which, for execution, give the greatest promise. 



Both as works of art and as drawings elucidatory of natural history, we 

 highly applaud Mr Audubon's system of representing his figures in all at- 

 titudes, because by doing so he has not only made most pleasing pictures, 

 but has exhibited all the important varieties in the plumage, and other cha- 

 racterestic points in the species represented. His fine taste in the arrange- 

 ment of the groups of flowers, plants, and water, where the feathered 

 tribes are represented employing themselves in their varied natural habits 

 and pursuits, marks a new era in the delineation of objects of natural history. 



Mr Audubon's graphic illustrations will be described afterwards, in a 

 Eeries of letters, in a separate work. 



BOTANY. 



16. Icones Filicum. — The tribe of ferns, universally celebrated as amongst 



