474 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



of timber, eight feet long and from six to eight inches be- 

 tween the upper and lower surfaces, are required to supply 

 this single item. The durability of ties varies, with climate, 

 kind of timber, soil, and usage, from four to ten years. As- 

 suming six years as the average life of a tie, the amount 

 required for annual supply must be 35,488,750 pieces, or 

 94,530,000 cubic feet. In considering this item it must be 

 remembered that a large amount of waste occurs from hew- 

 ing and other causes. It must also be borne in mind that 

 the demand for timber by railroads, besides that used for ties 

 and fuel, is enormous, including fencing bridges, buildings, 

 and other structures in great variety and number; that the 

 risk from fires is exceptionally great, and that our require- 

 ments in this direction are increasing even more rapidly 

 than our supplies are wasting away. 



GOLD -MINING IN THE PHILIPPINE ISLANDS. 



According to a letter from Minard to Daubree, the work- 

 ing of the auriferous quartz in the Philippines has been 

 abandoned, the alluvial deposits having proved much rich- 

 er in grains and scales of gold. It is associated with 

 fragments of dioritic rocks, as itaberite, with magnetite and 

 titanic iron, the gold occurring in tolerably large grains, 

 while quartz is seldom present. Native platinum is also 

 found with it, and, in the samples sent, small zircons with 

 quadrangular pyramids on each end were recognized, as 

 they usually occur in auriferous alluvium. 3 C, July 27, 

 1874,600. 



NEW CAEBONIC ENGINE. 



De Beins, of Amsterdam, has communicated the results of 

 his latest experiments with carbonic acid motive-engines. 

 He has for many years studied the question of the transfor- 

 mation of heat into mechanical power, and in seeking to as- 

 certain the degree of pressure evolved by carbonic acid dis- 

 engaged from bicarbonate of soda heated in a confined space 

 he found that when the bicarbonate of soda, or of potash, 

 either in the condition of dry powder or of an aqueous solu- 

 tion, was heated in a confined space, a part of the carbonic 

 acid became disengaged, and condensed in a cool part of 

 that space, in such a manner that at the temperature of 250 



