# Popular Science Monthly/Volume 81/August 1912/The Progress of Science

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THE POPULATION OF THE UNITED STATES IN 1910
The Bureau of the Census has now issued a bulletin giving the official figures of the thirteenth census, preliminary statements of which have from time to time been made public. The population of the United States was 93,402,151, of which 1,429,885 belongs to the non-contiguous territory of Alaska, Hawaii and Porto Rico and persons in the military and naval service stationed abroad. There are still to be added the inhabitants of the outlying possessions of the United States—some eight millions—nearly all in the Philippine Islands. The percentage of increase from the preceding census is 21, being three tenths of a per cent, larger than for the preceding decade. The population of the United States shows an increase of about one third during each of the seven decades from 1790 to 1860, of about one fourth during the three decades from 1860 to 1890 and of about one fifth during each of the last two decades. Thus while the increase in population over the preceding census continually increases, the percentage of increase becomes continually less, and there is no reason to suppose that the population will increase indefinitely. Indeed, if it were not for foreign immigrants and their larger families, the increment of increase of the population would he very small. It should, however, be added that there are those who hold that the native population would increase more rapidly if it were not for the large immigration.
The density of population and the increase of population, as shown on the accompanying maps, are very unequally distributed over the United States. There are ten states in which there were in 1910 a population per square mile of more than one hundred. Rhode Island with 508, and Massachusetts with 418 are the most densely populated
states, followed in order by New Jersey, Connecticut, New York, Pennsylvania, Maryland, Ohio, Delaware and Illinois. The least density of population is in the mountain states, Nevada with less than one inhabitant to the square mile ranking the lowest, followed by Wyoming and Arizona. The largest percentages of increase are shown by the mountain and Pacific states, Washington leading with an increase of 120 per cent., followed by Oklahoma and Idaho. As has already been widely noted, Iowa shows an actual decrease in population. The states of Missouri and Indiana show very moderate increases; the rural New England states also show small increases of from four to seven per cent. The increase in New-York is 25 per cent, and in Pennsylvania 22 per cent.
The urban population, which includes j those residing in cities of 2,500 inhabitants or more, has increased 35 per cent., and the rural population 11 per cent., seven tenths of the sixteen million increase being in the cities. The urban population is now 46 per cent.-of the total population, whereas in 1880 it was 29 per cent. The three cities—New York, Chicago and Philadelphia—having a population of more than one million, show thirty-two per cent, increase, while five cities, having a population of 500,000 to one million, show an increase of only 20 per cent. The cities—90 in number—having a population of 50,000 to 250,000 show the largest percentage of increase, namely, 41 per cent. In New England and the Atlantic states about three quarters of the people live in the cities.
THE ERADICATION OF HOOKWORM DISEASE
the individual from doing his ordinary work, reducing, it is said, his efficiency to less than half. A good part of the inefficiency, laziness and lack of enterprise of the white people of the south is attributable to the infection. It is further a disease which is both curable and preventable, and it is in such a case that medicine and hygiene have their great opportunity.
Some 75,000 persons were treated at the initiative of the commission, and much was accomplished by spreading knowledge as to the means of preventing soil pollution. Indirectly the commission has had the effect of awakening interest in health conditions throughout the south, so that state boards of health have become more active, and superintendents of health giving their whole time to the work have been appointed in various counties. The commission has also undertaken to obtain information in regard to the hookworm disease in foreign countries. In Europe, except in Italy, the infection is practically confined to miners, and is found in only a few well-defined localities, but in many tropical and sub-tropical countries the infection is extremely prevalent. It is said that 90 per cent, of the working population of Porto Rico are infected; on many plantations in Ceylon the infection rises as high as 90 per cent.; of the three hundred million of people in India 60 to 80 out of every hundred harbor the parasite, and conditions are nearly as bad in the southern two thirds of the Chinese Empire.
SYNTHETIC RUBBER
​principal constituent of india rubber, is based on a cluster of at least 10 or 20 molecules of the formula ${\ce {C_5 H_8}}$. It Thus possesses the same composition as oil of terpentine and other terpenes, which are the chief components of fusel oils. There is a hydrocarbon called isoprene which has the formula of ${\ce {C_5 H_8}}$, and it has for some years been known that when this volatile liquid is allowed to stand for some time in a closed bottle, it gradually passes into a substance having the principal properties of natural caoutchouc. The same change may be effected, as Professor Harries had shown, in an article published last year, by treatment with metallic sodium. Dr. Matthews independently made the same discovery. The difficulty was that isoprene is difficult to obtain and is more expensive than india rubber. Professor Fernbach, however, after eighteen months of research, discovered a fermentation process for the production of fusel oil, one of the raw materials of isoprene, from any starchy material, such that the cost will not exceed $150 a ton.
As is well known, the existence of india rubber was learned from the Indian tribes of South America, and the best rubber known, para rubber, still comes from Brazil. In recent years plantations of rubber trees have been set out, especially in Ceylon, and about 300 tons of rubber are produced annually as compared with 70,000 tons from the wild trees. The enormous increase in the commercial demand for rubber, due to many causes but first to electrical insulation and later to the introduction of automobiles, has made the natural supply inadequate and greatly increased the cost. It may be confidently expected that the demand will further increase in the future and that rubber could be used to advantage for many purposes if it could be obtained at less expense. The discovery of the possibility of artificial rubber at a cost that competes with natural rubber is consequently an important application of modern science.
SCIENTIFIC ITEMS
We regret to record the death of Dr. Shadworth H. Hodgson, the British philosophical author; of Dr. Ferdinand Zirkel, emeritus professor of mineralogy at Leipzig; of M. F. Lecoq du Bois-Baudran, the French chemist who discovered gallium; and of M. C. Andre, director of the Lyons Observatory.
A memorial service in honor of Bobert Koch was recently held in a temple dedicated to him, which has been erected at Tokyo. The temple owes its origin to the interest of Professor Kitasato.—Lady Hooker will be grateful if any who possess letters written by her late husband, Sir Joseph Hooker, will lend them to her for the purposes of a biography which Messrs. Smith, Elder and Co. will publish.
The nineteenth International Congress of Americanists to be held in 1914 will consist of two sessions: the first in Washington, D. . C, and the second at La Paz, Bolivia.—The International Geological Congress will hold its twelfth meeting in Canada during the summer of 1913. It is proposed to hold the meeting in Toronto beginning on or about the twenty-first day of August.—The program for the meeting of the British Association at Dundee on September-4 and following days includes garden parties at Glamis Castle, Kinfauns Castle, Rossie Priory and Camperdown and excursions to St. Andrews, Dunfermline, Arbroath and Aviemore. The president, Dr. Schäfer, of Edinburgh University, will devote his address to the developments that have taken place during the last fifty years through the study of the tissues of the body by means of the microscope. Professor Bragg will discourse on "Radiations, Old and New," and Professor Keith on "The Antiquity of Man."