AND BURNED LIMES CONTAINING IT. 233 



to be in the state of powder. It is easy to obtain it in this 

 state by causing it to flow into water as it issues from the 

 smelting furnace in which it is formed. 



2. With burned limes which contain silicate of lime. To 

 perform these experiments, the relative proportions of combined 

 silica in each of two limes should be ascertained, and compara- 

 tive experiments made with the two under similar circum- 

 stances. Or those who are really desirous of lending a helping 

 hand to this inquiry, may artificially mix a portion of siliceous 

 sand with the limestone as it burns in the kiln, and thus cause 

 the production of a portion of silicate of lime during the burn- 

 ing. With lime thus prepared, compared with pure lime, ex- 

 periments can readily be made.* 



It is a matter of very wide observation, that lime has the 

 effect of strengthening the straw. Some say that lime and 

 salt succeed better. But how this result is brought about 

 whether all varieties of non-magnesian lime act alike whether 

 the proportion of siliceous matter which a lime contains has 

 any connexion with this result whether the straw thus 

 strengthened contains more silica whether it is strengthened 

 only by having the rapidity of its growth diminished ; these 

 are questions in regard to which we have no experimental obser- 

 vations to guide us to a satisfactory answer. 



* The limes and limestones, of which the analysis has been given in 2, con- 

 tain comparatively little siliceous matter. Many, however, which burn very 

 well, and are in extensive use, contain much more. The following numbers 

 represent the composition of two limestones from the upper Ludlow rocks, on 

 the borders of Denbigh : 



No. I. No. II. 



Carbonate of lime, 83.58 69.07 



Sulphate of lime, 0.37 0.41 



Phosphate of lime, 0.14 0.12 



Carbonate of magnesia, .... 0.66 1.47 



Alumina and oxide of iron, . . . 2.67 5.24 



Insoluble siliceous matter, . '.''. 12.73 23.69 



100.15 100 



The limes produced by the burning of these limestones must contain much 

 silicate, and ought to be modified in their action, as compared with pure limes, 

 accordingly. The composition of others, containing still more silica, will be 

 found in The Use of Lime in Agriculture, p. 35. 



