J84 M. Repetti on Quartx Crystals and Siliceous Paste 



different places, and by various observers in the same place, 

 we cannot but view with suspicion the extraordinary coinci- 

 dence in the number 5° 53', which represents at three places 

 the difference of variation for 1S8 years ! The similarity be- 

 tween the differences of each period for the three different 

 places is also exceedingly suspicious. For example, from 

 1735 to 1742, the difference of variation is exactly 23' at each 

 of the three places of observation ; and in the following period, 

 from 1742 to 1745, the difference of variation is 4' at each of 

 the three places. Such a strange coincidence in the observa- 

 tions is not hkely to have taken place, even if the same obser- 

 ver and the same instrument had been the means of obtaining 

 them. 



It would be highly desirable, therefore, both for science 

 and for the credit of those gentlemen whose respectable names 

 are connected with this document, that its history should be 

 diligently inquired into. 



Art. IV. — Account of the Quartz Crystals, and the Sili- 

 ceous Paste Jbund in the Marhle of Carrara, as described 

 by M. Repetti. * 



The cavities containing different fluids which occur in seve- 

 ral species of crystals have only a few years ago attracted the 

 attention of natural philosophers. We have already publish- 

 ed on this subject several important memoirs by Sir Hum- 

 phry Davy and Dr Brewster. In the present paper, I pro- 

 pose to give an account of the curious results contained in a 

 work by M. Emmanuel Repetti, entitled Sopre Valpe apu- 

 ana ed i marmi di Carrara. I ought to inform those who 

 are not much disposed to admit, without strong evidence, 

 facts of which they do not understand the cause, that in Italy 

 the knowledge and sincerity of M. Repetti are well known. 

 The rock crystals found in the marble quarries of Carrara 



• This Analysis is translated from the Annates de Chimie, S^c. Jan. 

 1828, p. 86. The extracts only are from M. Repetti. See the following 

 article. 



