CHEMICAL MrSCXLLAMES. 155 



layer of bricks broken into acute-angled fragments. Thus Method of 

 two other strata are put in, before the last, which is of pure 5jJS5»2 

 cement. The mould being removed, the stones thus form- France, 

 ed are laid in heaps to dry, The lime being very greedy of 

 water, and quickly becoming solid, these stones are notlong 

 in forming a hard body fit for building. 



The lime is not very dear, being burned with pitcoal. 

 The labour is not dear, requiring only one strong man as- 

 sisted by two or three boys of twelve years old. The mate- 

 rials, being from old ruins, are cheap . and only one horse 

 js employed in this manufactory, which is not the only one 

 in the country. I believe others exist in Prussian Poland 

 where these stones are made with much more success, be? 

 cause fragments of basaltes, which are better adapted to form 

 a bolid body with lime and alumine, are there used. 



The pebbles of Boulogne would be still preferable, and 

 I doubt not with these artificial stone might be made equal 

 to natural stone in goodness. 



XVII. 



Letter from Mr* Link, Professor of Chemistry at Rostock, 

 to Mr. Vogel*. 



JL HAVE just examined the pollen of the hazel nut. It Pollen of the, 

 differs greatly from that of the date tree, which Messrs. haaelnut ' 

 Fourcroy and Vauquelin have analysed. It contains a large 

 quantity of tannin, a resin, a great deal of gluten, and a 

 little fibrin. There is animal matter therefore jn this pol- 

 len. 



To learn the properties of the membranous part of pith of elderc 

 plants, I subjected to research the pith of elder, and pro- 

 cured from it by nitric acid every thing, that Bouillon-La- 



• Annates dc Chimie, vol. LXII, p. 292. 



grange 



