# Popular Science Monthly/Volume 47/May 1895/Notes

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The leaves of pine and fir trees are inflammable—in strong contrast with the leaves of deciduous trees, which can not be made to burn at all while green—because of the pitch they contain, which consists of fats and ethereal oils, and compared with which the proportion of water is small. When the leaves burn, the water is at once converted into steam, and causes the explosions, snapping, and spitting of fire for which burning coniferous trees are remarkable. Dry fir leaves, although they burn very rapidly, do not exhibit these explosions, because there is no water in them. The rending of tree trunks struck by lightning is in like manner supposed to be caused by the steam evolved from the sap suddenly heated by the electric force.
M. Saccado, a botanist of some fame, computes the number of known species of plants to be 175,700, including 105,251 phanerogams, 2,819 ferns, 565 other vascular cryptogams, 4,609 mosses, 3,041 liverworts, 5,600 lichens, 39,603 fungi, and 12,178 algæ; and he guesses that the whole number of fungi is perhaps as much as 250,000, and that of other plants 135,000. It is proper to observe that the author is a specialist in fungi, and is therefore perhaps predisposed to make a liberal estimate of their number.
The International Meteorological Committee, at its recent meeting in Upsala, Sweden, decided upon the publication of a cloud atlas, to be in English, French, and German.
The educational conference of a week, held last summer at the Summer School of Applied Ethics, Plymouth, Mass., was so successful that it has been decided to transform it into a department of the school. The special direction of the department has been assigned to a committee of three experienced teachers, and the sessions will begin near the end of July and close about August 12th. This new department does not enter into competition directly with existing summer schools, for the aim is neither to give instruction in the school subjects nor in the theory, history, and art of education, but to consider education as a social force and its relation to other social forces.
The Deseret professorship of geology in the University of Utah has been endowed, as we learn in a note from Dr. James E. Talmage, the incumbent of it, with sixty thousand dollars by the liberality of the Salt Lake Literary and Scientific Association—not by the city, as was stated in a recent note in the Monthly. The Literary and Scientific Association is a body incorporated for scientific pursuits which has existed for several years in Salt Lake City.
Recent dispatches from Europe state that argon, the newly discovered element in the air, has been found by Prof. Ramsay in combination in a mineral containing the extremely rare elements yttrium and erbium; associated with it was another gas which under Prof. Crookes's spectroscope gave a spectrum identical with that of the hypothetical element helium, which has been found in the spectrum of the sun and of the aurora borealis, but, till this time, nowhere else. M. Berthelot has, by means of the electric spark, effected a combination of argon with benzene.
A new weed has become common and abundant through a large part of the central Southwestern States. It is described by J. C. Arthur, of Purdue University Agricultural Experiment Station, under the name of Lactuca scariola wild or prickly lettuce as an annual, related to the garden lettuce,—but bearing prickles on parts of the leaf and stem, and blossoming in July and August. It has all the qualities needed to insure its survival—producing many seeds, feathered for wind-carriage and ready to grow, sprouting abundantly when cut, and tenacious in its root hold. It is of curious botanical interest as having, like the silphium or ​compass plant, the property of twisting its stem leaves into a vertical position, with the edge directed north and south. It is one of two well-marked compass plants. It is not likely to be exterminated, and can at most be kept down by timely mowing and uprooting.
The result of an inquiry by Dr. J. S. Cameron, of Huddersfield, England, into the conditions of the dwelling as affecting recovery from measles, points to the conclusion that fresh air provided by a through draught tends to produce recovery when measles has attacked the family; while overcrowding, dirt, and structural or other insanitary conditions assist in bringing about a fatal result.