The decantation furnishes│1st.—A deposit of fine calcareous│3.14 grams. │sand weighing dry │ „ │2nd.—Clayey liquid giving after coagulation │by acid, filtration and drying 0.85 grams of │clay. │ │ Then: Total fine elements │5.13 grams. Fine elements determined │Fine calcareous sand 3.14│3.99 „ directly. │ │ „ │Clay 0.85│ „ │ │———— Fine calcareous sand by difference │1.14 „ Calculating these results to the original quantity of 1,000 grams the following data are obtained: RÉSUMÉ. One thousand grams of dry earth contain: Pebbles 21 grams. Gravel 33 „ Organic débris 1 gram. Fine earth 945 grams. ———— Total 1000 „ 945 grams of │Coarse sand 432 gms. │Noncalcareous sand 305 gms. fine earth │ │ contain: │ │ „ │ „ │Calcareous sand 119 „ „ │ „ │Organic débris 8 „ „ │ „ │Fine elements 513 gms.│Fine, noncalcareous sand 314 gms. „ │ „ │Clay 85 „ „ │ „ │Fine calcareous sand 114 „ │ │ —— │ │Total 1000 „ There are counted as clay all the elements which have remained in suspension in the water after a period of repose of twenty-four hours. In fact, these elements comprise a notable proportion of very fine sand which is not deposited during that time. In order that the liquid should become entirely freed from this sand it would be necessary to wait several weeks and even several months. Such a prolongation of the analysis is evidently inadmissible. The period of twenty-four hours of repose therefore has been adopted. This is merely conventional, in the same way that the period of ten seconds adopted for the precipitation of the gravel is conventional. But this convention is justified by the fact that the substance which is called clay presents, when it has a proper degree of humidity and cohesion, a plasticity entirely analogous to that property of natural clay. Moreover, as has already been said, that which is chiefly important in these analyses is the employment of processes always comparable among themselves in their results and generally followed.