Chemical Science. 411 



Hence camphor appears to act like a simple body, and there is no 

 other case of a similar kind amongst organic bodies, except with 

 indigo *. 



19. ACTION OF HEAT ON ACETATE OP LEAD. (Matteuci.) 



When acetate of lead is heated it fuses at 135J F., and boils at 

 212. During the ebullition it loses its three proportionals of water, 

 and solidifies nearly at the same temperature. When the tempera- 

 ture is still further raised fusion re-occurs at 536 F., the liquid boils 

 for some. time, becomes brownish, and again solidifies into a dull 

 white uncrystalline mass, which is a trisacetate of lead. During the 

 operation, acetic acid, with a little pyroacetic spirit, comes over, but at 

 a later period only pyroacetic spirit, with abundance of carbonic acid, 

 is obtained. 



The pyroacetic spirit being analysed was found to contain hydrogen 

 6.4039 ; carbon 59.86 ; and oxygen 33.7361 per cent.=to 3:5:1 

 volume of these substances. This composition may be represented 

 by 1 proportion of acetic acid 1 of water, and a substance composed 

 of 6 proportions of carbon and 2 of hydrogen. Pyroacetic spirit soon 

 begins to decompose, and when exposed only a few minutes to the 

 air, becomes acid and milky ; acetic acid and an oleaginous body (in 

 appearance) are produced. When heated in contact with potassa or 

 lime, acetates are formed and the oleaginous substance evolved. With 

 chlorine it produces muriatic and acetic acids, and the same oleaginous 

 body. The oleaginous principle has an aromatic odour, and by 

 exposure to air becomes green ; it is insoluble in water, but soluble 

 in alcohol. It contains no chlorine, but is a binary compound of 

 carbon and hydrogen f. 



$ III. NATURAL HISTORY. 



1. INDUSTRY OF BIRDS. 



DR. STEEL, who resides near the mineral springs of Saratoga, has 

 observed, that the river swallow (Hirundo riparid) can, when neces- 

 sary, vary the construction of its nest. When it finds steep sandy 

 banks, it excavates them, forming holes for its nest to which its 

 enemies cannot obtain access. But when such a bank is wanting, it 

 approaches the habitations of men, and though less familiar than the 

 window swallow, it attaches its nest to granaries, cart houses, and 

 similar places. Then it is obliged to build instead of excavate, and 

 it does in fact gather materials and put them together. It appears 

 too that this species has not essentially the habitudes indicated by its 

 name : it can live and thrive wherever it can find subsistence, security, 

 and society ; (for isolated familes or solitary nests do not occur.) A 



* Ann. de Chimie, xlvii. p. 95. t Ibid., xlvi. p. 429. 



