CHEMICAL SCIENCE. 303 



under the oxidating action of the air, and all the impurities are eliminated by 

 the crystallization which has taken place in the mass ; there arc formed in 

 this manner two very distinct layers, which it is easy to separate. 



This operation could perhaps be applied with advantage in purifying crude 

 rock salt, as well as ordhuuy sea salt. 



The fusion of the salt in contact with the air, or out of the air, will explain, 

 to a certain extent, how it is that the salt found in the bosom of the earth is 

 generally contaminated with coloring matter, and how, on the contrary, that 

 which is exposed to the oxidating action of the atmosphere is white and 

 transparent. 



From these facts we cannot determine as to the origin of the formation of 

 rock salt, for, by fusion, we can obtain salt having a transparent appearance, 

 with physical properties defined ; but the presence of organic remains envel- 

 oped in the natural product excludes the probability of its being formed by 

 igneous fusion ; besides, it is difficult to imagine, if the mass had really been 

 in a state of fusion, why it was that the chloride of magnesium was not de- 

 composed. As to the phenomena of decrepitation which lias been observed 

 to a certain extent in rock salt, the same has been noticed in salt crvstallized 



* 



in the wet way, therefore this cannot confirm the hypothesis of igneous for- 

 mation. 



Without pretending to decide the question of origin, these experiments 

 show a product analogous, if not identical, with natural rock salt 1\1. Mar- 

 yueritte, Comptes liendus. 



NEW AXD CURIOUS GUANO PRODUCT. 



At a recent meeting of the Boston Society of Natural History, Dr. A. A. 

 Hayes exhibited some specimens, resembling Trachyte rock so closely, that 

 most observers would have mistaken them for Trachyte. 



The specimens consisted of hand specimens, having the uneven fracture of 

 trachyte, full of capillary passages, with some cavities ; there were fractured 

 planes of brown and flesh-colored minerals, resembling felspar, and some 

 small red, brown-colored and black granules ; but the most characteristic mark 

 was the occurrence of angular fragments and grains of yellowish green color, 

 hardly distinguishable from epidote by the eye. The external surface was 

 brown and uneven, like that of a weathered basalt, or trap. The island from 

 which these specimens came has been examined by a geologist, and from 

 the prevalence of this rock, it is said that he pronounced the island to be of 

 volcanic origin. A mass was sent to Dr. Hayes, and he found it had struc- 

 tural planes, the divisions producing trapezoidal masses, their surfaces and 

 the lines marked by darker colors, and, so far as could be determined, there 

 was evidence of the mass being part of a rock formation of some extent. 



The chemical composition discloses the remarkable fact that this rock 

 is composed essentially of fish bones and altered shells, which have passed 

 through the alimentary canals of sea fowls. Inferring to communications 

 before made,* Dr. Hayes stated that the organic matter of fish bones in the 



* See Annual of Scientific Discovery for 1857, pp. 242, 243, 244. 



