PLASTER THRESHING FLOORS. , 363 



XII. 



Description of the Mode of making Threshing-Floors in the 

 Commune of Valbonnais, in the Department of the here: 

 by Mr. J. J. Chamjpollion Ficeac, Secretary to the 

 Society of Sciences and Arts at Grenoble, Sfc. *. 



JL HE gypsum quarries of Valbonnais furnish two sorts of Tw <> sorts of 



gyusum 

 plaster, one white, the other reel. The white is found The red used 



only in solitary strata, not very abundant : the red, which *° r floors. 



is coloured by oxide of iron, is the most plentiful, and used 



almost exclusively for threshing floors. 



For this purpose it is burned for 24 or 30 hours, pound- Calcined, pow- 

 ed as fine as possible, and in this state left for ten days, j^?' ex P osed 

 before it is used. It is to be observed, the more it is 

 burned, and the finer it is pounded, the better it is. At well mixed 

 the expiration of this term, and after the ground on which 

 the floor is to be formed has been made very level, the 

 plaster is to be diluted with cold water in a bucket. It 

 must be carefully mixed so as not to have any lumps. 



Two feet from one of the walls of the barn, and parallel A slip of wood 



to it, a ruler is to be placed, of the height which the £ Iacec ? tw0 * et 



7 . ' from the wall, 



plaster floor is intended to have. This is commonly two and the plaster 



inches and half, or three inches. When the plaster is quite-]". 8 . 1 ha, d enin £ 

 imooth, has acquired a certain degree of consistency, and terval and 

 »s almost beginning to dry, it is poured out on the space sm00thed - 

 between the wall and the rules. To level it another ruler 

 is passed over it, one end of which rests on the former, 

 the other touches the wall. It is then gone over with a 

 trowel, to make it as smooth as possible, every vacuity 

 is filled up, and any heterogeneous matters, that may be 

 on the surface, are removed. Thus a smooth level sur- 

 face is given to it, which is an essential quality. 



As soon as this is done, a similar quantity of plaster This is repeated 

 prepared in the same manner is laid at the end of the for- 

 mer, and the same operations are repeated, till the plaster 

 is extended to the opposite side of the barn. Here, how- ^^ within afe ^" 

 ever, it is absolutely necessary, to leave a little void space, opposite wall. 



* Sonnini's Bibliotheque Physico-economique, Feb. 1807, p. 315. 

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