REVIEWS. 411 



carbonate of thallium in hydrofluoric acid containing much silicic 

 acid. The salt is very soluble, and the formula has not been accu- 

 rately ascertained. 



From the above it will be seen that thallium well deserves the name 

 given by Dumas — fehe " Ornithorhyncus of Metals," exhibiting about 

 equally the characters of lead and potassium. The solubility of the 

 oxide would lead to its being ranked among the alkalies, but it must 

 be remembered that oxide of lead is not quite insoluble ; and mag- 

 nesia is ranked with baryta although virtually insoluble in water. 



The solubility of the sulphate would tend to rank it with the alka- 

 lies, but the opposite character of the haloid salts and of the chromate 

 would point to its classification with lead and silver. The existence 

 of an octohedral alum would be greatly in favour of the first view, 

 were it not that a silver alum has been prepared, but the existence of 

 the magnesian sulphate containing thallium instead of potassium or 

 ammonium is perhaps the strongest fact yet discovered in favour of its 

 alkalic nature. 



Thallium may be said to form one of the most curious connecting 

 links between different classes of metals, standing between the lead 

 group, to which it assimilates in its physical and many chemical pro- 

 perties, and the potassium group to which it is evidently closely re- 

 lated. 



For analytical purposes it must be ranked in the second division of 

 the second group, among the metals precipitated by hydrosulphuric 

 acid from alkaline solutions, and forming sulphides insoluble in sul- 

 phide of ammonia. 



H. C. 



Almanaque para el/ino de 1863, calculado para los Estados Unidos 

 de Colombia por Indalecio Lievano, JEncargadb del Ohservatorio 

 Asironomico de Bogota. Imprenta de echeverria Hermanoa. 

 Bogota. 1862. 



A thin duodecimo of 64 pages bearing the imprint "Bogota." 

 Perhaps some of our readers would be puzzled to tell at a word 

 where or what Bogota may be. Our pamphlet might inform them 



