1172 OYSTKRS, AND ALL ABOUT THEM. 



" M. Liazard states : ' It was necessary to find a substance 

 which, placed between the outer coating of the tile would 

 decompose after remaining long in the water, and thus 

 leave the coating almost free. I tried different pastes, all 

 of which gave good results, but it was necessary to select 

 the most economical. I was satisfied with a mixture made 

 of flour and a small quantity of the scrapings of potatoes, 

 boiled in a sufficient quantity of water to produce a thin 

 paste. The tiles were dipped in this, and after they were 

 dry they were passed through a bath of hydraulic cement. 

 I have always succeeded with this mixture ; it is quickly 

 made and costs but little. Every time I have neglected to 

 use it I have regretted it.' 



" M. Alphonse Martin says : * I first plunge each tile 

 into a milk of quicklime, and when this coating is quite 

 dry I again dip the tile into a bath of hydraulic cement.' 



" M. de Wolbock generally uses two layers of hydraulic 

 cement." 



" It seems to us rational that, when not intending to 

 leave the oyster attached to the tile, we should resort to 

 two layers, the first of quicklime, which will not adhere 

 very firmly, and the second of hydraulic cement. The first 

 facilitates the removal of the oyster and the second the 

 adherence of the young." 



Tiles may be used as spat collectors in either deep or 

 shallow water. On the French coast they are chiefly 

 employed above low tide mark, or very shallow water, and 

 they are then spread out on a considerable area. In some 

 cases lines of stakes are driven into the ground, about a 

 foot apart, transverse string pieces are fastened to them 

 about a foot above the bottom, and a row of tiles is laid 

 upon the latter, concave surface down, another row of tiles 

 is placed at right angles upon the first layer and the whole 



