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To the Building Committee of the SmitJisonian Institution, on the action 

 of frost wpon certain materials for huilcliiii. 



>S- 



Of the twenty-five specimens of stone submitted to me for examination 

 with reference to their relative properties in resisting the disintegrating 

 action of frost, I have been able to investigate but twenty-two ; the remain- 

 ing specimens, marked, respectively, 1, 9, 5 D, being too small to submit to 

 the test. It was thought desirable to ascertain their specific gravities, with 

 a view to determine if any connexion existed between their densities and 

 liability to dilapidation. The result leads us to infer that such relation does 

 not exist, and that the texture of the stone, without reference to density, 

 determines its frangibiliiy under the influence of frost. Resort was had in 

 these experiments to an imitation of the operation of freezing water after 

 the process described by Brard, a French chemist, in the '' Annales de 

 Chiniie et Physique,^'' vol. 38. The details of the process will presently 

 be given. 



The absorption and subsequent freezing of water within the stone would 

 liave been a more energetic mode of action; but the undertaking would 

 prove one of considerable practical difficulty, and, on the whole, not so 

 reliable as an experiment, unless, perhaps, the cn-cumstances were such as^ 

 to admit of their exposure to natural freezing under favorable circumstances. 



The process of Brard consists in substituting the crystallization of the 

 sulphate of soda for the freezing of water, and has met with the approval 

 of many French architects and engineers, as the results accord with their 

 experience. In the freezing or crystallization of water, the expansion is 

 such, that the crystals float; while in the crystallization of sulphate of soda, 

 and other soluble salts, the crystals sink in the solution; but, notwith- 

 standing, the exertion of the crystalline forces of these salts is sulhcient to 

 produce decided impressions upon the hardest of building materials in a 

 izw weeks. 



The specimens of s^tone furnished me by your board were all numbered 

 as according to the subjoined table; and it may be proper to remark, that 

 their localities and respective values, as usually estimated, were unknown 

 to me until after the results ol the experiments had been laid before you 

 and approved. 



Six numbered specimens were also handed to me by Mr. Dewey, and 

 are marked, respectively, ID, 2 13, (fcc. The specimens were cut into 

 inch cubes; three of the whole number being of. insufficient size, were laid 

 aside, as above mentioned. The cubical blocks, suspended by strings, to 

 which the respective numbers upon labels were attached, were first im- 

 mersed in a boiling solution of sulphate of soda, saturated when cold; and 

 after remaining half an hour in tlie boiling liquid, they were removed 

 and hung upon a frame over half-pint bowls, containing also a quantity of 

 tile cold saturated solution. 



In the course of 24 hours a considerable efliorescence was found upon 

 the surface of each specimen, consisting of the crystals of the salt mixed 

 with comminuted portions of the stone. These were washed off daily, by 

 simultaneously innnersing the stones in the solution in the bowls, and suf- 

 fering them to remain there for a few minutes. This proceeding was re- 

 peated daily for one week, when it became necessary to deviate from Brard's 

 directions, and to keep them in a moderate temperature, instead of a cold 

 cellar, as he advises. It was obvious that the investigation would be ex- 



