MR. W. J. ROSE said Mr. Shellshear was to be complimented on having written, so far as he (Mr. Rose) was aware, the first really scientific attempt to elucidate the mysteries of concentrating mill-slime. He makes every effort to define the conditions under which his experiments were made; he presents his results in an easily comprehensible manner, and does not attempt to base any theory on admittedly incomplete data. The real scientific value of such a paper far outweighs that of the most brilliant a priori exposition of weird and quite unsupported theories. One opinion of his, however, might be challenged and that was with regard to the necessity for standard definition of slime. There could be no doubt that in most cases, in crushing ore, portion of it was reduced to a state of subdivision in which it presented certain differences from the rest, such as were scarcely to be explained merely by the smallness- of the particles. That was the only true slime, and a definition to be tenable must be based on a complete understanding of those differences, and their causes.