200 Miscellanies. 



by credible witnesses that it can scarcely be doubted. As for myself, 

 my credulity is compelled to yield to the discovery I made one day 

 of a small fish, in my pluviometer, which was situated on an isolated 

 pile of stones about five feet high, in my garden at Benares. A note 

 from M. Cameron informs me that a rain of fishes occurred on the 

 19ih of February, 1830, near Feridpoor. This fact was asserted 

 before a magistrate, by many ocular witnesses, and it was their con- 

 curring testimony that towards noon of the above mentioned day, the 

 sky was obscured, the rain commenced to fall, and shortly after, 

 fishes of various sizes fell from the atmosphere. A large number 

 were collected by several witnesses ; some were found destitute of a 

 head, and had commenced to putrefy ; others were entire and fresh, 

 but no one dared to eat them. — Bib. Universelle, JVo. 3, Mars, 1836. 



15. JVatwe of different Cements. (Berzelius's Jahresbericht, etc. 

 xivth year, 1st number.) 



Fuchs has studied the nature of different species of mortars, and 

 demonstrated that their solidification depends on the formation of 

 silicate of lime, and sometimes also of silicate of alumine. These 

 silicates retain some water and assume the firmness of stone, whilst 

 the hydrate of lime in excess unites by degrees with carbonic acid ; 

 and consequently solidified mortar may be considered a compound 

 of carbonate of lime and of a zeolite. Opal, pumice stone, obsidi- 

 an and pitch stone pulverized, form with hydrate of hme a good ce- 

 ment. But only the surface of each grain of quartz or sand, is 

 transformed into a hydrated silicate, and though this is sufficient to 

 unite the mass, solidification does not take place so promptly. The 

 mass becomes the more solid, the more finely the quartz is pulveri- 

 zed. If the pulverized quartz be mingled with one fourth part of 

 lime, and after thoroughly calcining the mixture, it be pulverized and 

 mixed with one fifth part of lime, it forms a hydraulic cement which 

 becomes so hard as to be susceptible of a polish. Feldspar hardens 

 slowly, and with lime only after five months ; but if calcined with a 

 little lime it is much improved. Common potter's clay, which is 

 absolutely worthless in its natural state, affords with lime, when cal- 

 cined, provided it contains but little iron, a cement which readily 

 hardens. 



Fuchs having discovered that steatite, which had been subjected 

 to a red heat, could not be made to unite with lime, and thence con- 

 cluding that magnesia has a strong affinity for silicic acid, attempted 



