MANUAL OF ASSAYING GOLD, SILVER, COPPER, and Lead Ores. By Walter Lee Brown, B.Sc. Revised, Corrected, and considerably Enlarged, with a chapter on the Assaying of Fuel, &c. By A. B. Griffiths, Ph.D., F.R.S. (Edin.), F.C.S. Crown 8vo, cloth, Illustrated, 7_s._ 6_d._ _Colliery Guardian._--“A delightful and fascinating book.” _Financial World._--“The most complete and practical manual on everything which concerns assaying of all which have come before us.” GEODESY. By J. Howard Gore. Crown 8vo, cloth, Illustrated, 5_s._ _St. James’s Gazette._--“The book may be safely recommended to those who desire to acquire an accurate knowledge of Geodesy.” _Science Gossip._--“It is the best we could recommend to all geodetic students. It is full and clear, thoroughly accurate, and up to date in all matters of earth-measurements.” THE PHYSICAL PROPERTIES OF GASES. By Arthur L. Kimball, of the Johns Hopkins University. Crown 8vo, cloth, Illustrated, 5_s._ _Chemical News._--“The man of culture who wishes for a general and accurate acquaintance with the physical properties of gases, will find in Mr. Kimball’s work just what he requires.” HEAT AS A FORM OF ENERGY. By Professor R. H. Thurston, of Cornell University. Crown 8vo, cloth, Illustrated, 5_s._ _Manchester Examiner._--“Bears out the character of its predecessors for careful and correct statement and deduction under the light of the most recent discoveries.” LONDON: WILLIAM HEINEMANN 21 BEDFORD STREET, W.C. TRANSCRIBER’S NOTES The *** character was originally printed as an inverted asterism. Page numbers in the Index of Authors have been changed from Arabic to Roman because they duplicated page numbers in the work itself. In plain-text version, showed italics as _, and ignored boldface and small caps markings. Changes made to text: On page 66, changed “improve ” to “improve.” On page 75, changed “sold” to “sold.” On page 148, changed “you.” to “you.’” On page x, changed “origina talent” to “original talent”