343 



analysis of this marble, and passed specimens through the sever- 

 est ordeals, to ascertain the durability of the stone, which proved 

 to be capable of withstanding heat, cold, and all the usual acids 

 and salts. 



All these facts concerning the various Serpentines and Verd 

 Antique Marbles were published soon after the work was exe- 

 cuted, and these publications Dr. Jackson believes to have been 

 the first in which these localities of workable Serpentine and 

 Verd Antique Marbles, above named, were described* 



Prof. William B. Rogers remarked that he had been much 

 interested in the facts which had been disclosed in regard to the* 

 composition of this material, especially in the statem^t of Dr. 

 Hayes, that the substance of the white veins was nearly pure an- 

 hydrous carbonate of magnesia, and that neither it nor the green 

 matter contained any carbonate of lime. He had recently made 

 a qualitative analysis of the white substance, and also of the 

 clear rhombic crystals occurring in little groups in the midst of 

 it, and had found both to consist of carbonate of magnesia, with 

 some proto-carbonate of iron, but without any distinct trace of 

 lime. In these experiments, he was struck with the resistance 

 presented by the white matter of the veins to the solvent action 

 of hydrochloric acid, a fact auguring well for the durability of 

 even this part of the rock in many of its applications. 



Dr. H. R. Storer asked if any change had been noticed 

 in the Cochituate Water recently. He had observed that 

 the water in his father's house, in Winter Street, was 

 impure. 



Dr. Bacon had noticed a slight impurity in the water, 

 .for a few successive days, a short time since. 



Prof. Rogers had collected upon a cotton filter, a con- 

 siderable quantity of foreign matter, but no odor was 

 detected in it. On standing, however, for some time, 

 at a temperature of 65 degrees, a peculiar odor became 

 quite apparent. 



Dr. Jackson suggested that, in some instances, the 

 impurity of the water might be occasioned by impurity 



