October 20, 19 10] 



NATURE 



511 



tappi'd with a V-cut f^ave much less than others with a 

 vertical cut, the greater yield, however, being partly due 

 to the fact that the length of the incision in the latter 

 case is greater than in the former. No advantage 

 was gained from the use of four cuts daily instead of 

 two. The effects of nitrate of soda on the flow of latex 

 have also been studied. Fertilisers are in use in rubber 

 plantations for increasing the growth and vigour of the 

 trees, and it now appears that nitrate of soda also increases 

 the flow of latex. In one experiment a group of five trees 

 yielded oi) oz. of dry rubber in three days before apply- 

 ing the nitrate, and 1-3 02. in the three days following its 

 application, each tree receiving half a pound of the 

 fertiliser. How far the method is economical has yet to 

 be determined. All these experiments were made with 

 Oara rubber trees. 



.A number of analyses have been made of the latex from 

 the plants growing' in the Botanic Gardens, Singapore. A 

 thirty-two-year-old tree of Hevea brasUiensis gave at one 

 tapping 27 fluid ounces of latex, of which 6108 per cent, 

 was water, 23 per cent, serum solids, mainly organic 

 matter, and 3b29 per cent, coagulum was obtained by 

 means of acetic acid. Almost the whole of the coagulum 

 was rubber, only a little resin being present. From another 

 variety, Landolphia Heiidelotii, the dry rubber yielded 

 89-5 per cent, of pure rubber and 10-5 per cent, of resin. 



The question of preparing the rubber after the latex is 

 obtained is of very great importance. Fine hard Pari 

 rubber containing 10 or 20 per cent, of moisture has a 

 higher relative value than the practically pure sheets from 

 the East. It is considered that the difference in value is 

 partly due to the difference in method of dealing with 

 the latex, and a process has recently been devised in 

 which the latex is treated with smoke, creosote, and acetic 

 arid, so that it may coagulate under conditions comparable 

 with those obtaining in Brazil. In this process, steam at 

 a pressure of 30 or 35 lb., mixed with the fumes from 

 strongly heated green palm leaves or other green parts of 

 trees, is forced by a steam injector into tanks containing 

 the strained latex. In about ten minutes the caoutchouc 

 globules coagulate and rise to the surface. 



An incidental problem is the most economical way of 

 dealing with a rubber plantation until the trees come into 

 yielding. A Bulletin from the Federated Malay States 

 Department of .Agriculture sets out the advantages of 

 Coffee robiista. This plant, discovered wild in the Congo 

 region in i8qR. grows more rapidly and fruits sooner 

 than the well-known C. liherica. When grown in 

 rubber plantations, it yields a small return in the second 

 year and a good return in the third and following years, 

 but after five years it competes so seriously with the rubber 

 that it must be cut out. 



THE MINERAL RESOURCES OF THE 



UNITED STATES^ 



T \ response to the latest of the periodic scares of im- 



pending bankruptcy due to the exhaustion of fuel, ore, 

 or soil, the Geological Survey of the United States has 

 been instructed to estimate the national economic mineral 

 resources. Its report (Bull. No. 394), dealing with quanti- 

 ties on a continenial scale, may excite the envy of the single 

 countries of Europe: and though the factors are uncertain, 

 the available supplies of most minerals are sufficient to 

 render political restriction of output unnecessary. Thus, in 

 the case of coal, Pennsylvania is known to have enough to 



1 Uniud States Geological .Survey. Bull. 347.— M. R. Campbell. Con- 

 tributions to Economic theology, 1Q07. Pait Vi.. Coal and Lignite. Pp. 444, 

 XXV pis., 7 figs. (Washington : Government Priming Office, 1903.) 



Bull. 347.— F. E. Wright and C. W. Wrisht. The Ketchikan and 

 Wrangell Mining Districts, Alaska. Pp. 210+v, xii pis., 23 figs. (Wash- 

 ington : Government Printing Office, 190S.) 



Bull. 374.— F. H. Moffit and A. G. Madclren. Mineral Resources of the 

 Kolsina-Chitina Region, Alaska. Pp. 103, x. pis., 9 figs. (Washington : 

 Government Printing Office. 1909 ) 



Bull. .379.— A. H. B.ooks and others. Mineral Resources of Ala.ska, 

 Report on Progress of Investigations in 1908. Pp. 418, x pis , 21 figs. 

 (Washington : Government Priming Office, 1909 ) 



Bull 380.— C. W. Haves and W. I.indgren. Contributions to Economic 

 Geology, 190S. Part 1, Metals and Non-metals, except Fuels. Pp. 406, 

 it pis., 32 figs. (Washington : Government Printing Office, 1909 ) 



Bull. 394.— Papers on the Conservation of Mineral Resources. Reprinted 

 from Report of the National Conservation Commission. February, 1909 

 Pp. 214, .vii pis., 2 figs. (Washington : Government Piinting Office, igcq) 



NO. 2138. VOL. 84] 



last for 492 years at the rate at which the material was 

 being exhausted in 1907. Ohio has only used 09 per cent, 

 of its proved supplies, and at the rate of production in 1907 

 they will last for two thousand years. In Maryland the coal 

 will last for another 948 years. Mr. Gannet, in a general 

 summary of the extent of the coal reserves, estimates that 

 only one-third of one per cent, of the known and easily 

 accessible supply was mined during the last century. 



In regard to the other fuels, the future is less assured 

 for natural gas and petroleum. Assuming that petroleum 

 generally comes from beds 5 feet in thickness, and with 

 10 per cent, of pore space, an acre would yield 5000 barrels 

 of 42 gallons each. The extent of proved oil land in the 

 States is enormous. Thus, it is expected that the State of 

 California alone will supply 5,000,000,000 barrels. There 

 has been a steady increase in the yield from 2000 barrels in 

 1859 to ib6,ooo,ooo in 1907. The yield, how'ever, has 

 fallen in many of the States, including Pennsylvania and 

 New York, where, according to Dr. Day, it w'ill be 

 negligible ten years hence. The yield has fallen in Ohio, 

 West Virginia, Kentucky, Colorado, Indiana, Texas, and 

 Louisiana ; but it has risen in California, Illinois, and 

 Kansas. Dr. Day concludes that if the present prodiiction 

 is not increased, the available supply will last the States 

 for ninety years ; but if the demand increases as rapidly as 

 during the past few years, the end may come in 1935. He 

 therefore suggests that oil should be limited to the purposes 

 for which it is indispensable, such as lighting in scattered 

 houses and as a lubricant. As half a pint of oil is used in 

 an engine for every ton of coal burnt, the exhaustion of 

 cheap lubricants would be an industrial disaster. 



Dr. Day reports on the supplies of natural gas. In most 

 cases the wells have a short life, and 1,000,000,000 cubic 

 feet are still being wasted daily. Much of the waste is 

 said to be unavoidable, as the gas cannot be saved 

 economically from wells from which oil is being pumped ; 

 but legislation to prevent unnecessary waste is recom- 

 mended. After a well has ceased to yield gas under high 

 piessure, a supplv can be obtained for years by pumping. 



A mineral famine in the United States is most often 

 predicted for iron, as the ores of present value are 

 restricted in depth. The estimates compiled by Mr. 

 Hayes show that there is no immediate fear of the end of 

 the' Iron age. He estimates the ore supply now available in 

 the United States at 4,788,000,000 tons. If the_ present 

 rate of increase in the consumption of iron be maintained, 

 this quantity would, however, be used during the next 

 thirty vears ; so that before 1940 American iron production 

 w^oul'd ' have begun to decline, and low-grade ores not 

 included in the estimate quoted would have to be used. 

 Mr. Hayes, however, concludes that the factors are so 

 indeterminable that any further prediction as to the date of 

 exhaustion of American iron ores " is so uncertain as to be 

 wholly unprofitable and unwarranted." 



The United States have been one of the leading pro- 

 ducers of phosphates since 1867, and nearly half the 

 phosphate manufactured is exported for the benefit of the 

 exhausted soils of Europe. At the present rate of increase, 

 the supply will only last twenty-five years, and Mr. van 

 Horn, the author of the report on phosphates, therefore 

 recommends that future leases should only be granted on 

 condition that the phosphate shall be used in the States. 



That predictions of a coal famine in .America are idle 

 may be realised from the reports on the little-known 

 coalfields of the western and central States in Bulletin 341. 

 It is edited by Mr. Marius R. Campbell, and includes 

 twenty-two separate memoirs and a bibliography. The 

 coals 'are partly Eocene, belonging especially to the Fort 

 Union Series, and partiv Cretaceous, coming mainly from 

 the Mesaverde Series, the Sentinel Butte Field in North 

 Dakota and Montana yields an Eocene lignite, of which 

 33,000,000,000 tons are 'available within a thousand feet of 

 thj surface, and in seams 3 feet or more in thickness. 

 The coaj yields excellent producer gas, and can be made 

 into briquettes without the addition of any binder. The 

 coal contains 34 to 45 per cent, of water, and after it is 

 air-dried its calorific efficiency is from 8200 to 8600 British 

 thermal units. From Sentinel Butte a series of coal fields 

 extends south-westw'ard through Montana, Utah, Colorado, 

 Nev.ada, and New Mexico, the Eocene coals become less 

 important, and the Cretaceous coals more important to the 



