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THE POPULAR SCIENCE MONTHLY. 



isfactory manner. In the undyed state it is 

 the most lustrous of all silks, and is very 

 strong. Some of the prints obtained by 

 Mr. Wardle are beautifully suited to wall- 

 hangings, curtains, coverlets, and all kinds of 

 furuiture-work ; and, while the material has 

 not quite the brilliancy of the mulberry silk 

 in its printed state, it has a richer and softer 

 surface than those of cretonnes or challis, 

 while its lasting qualities are superior to 

 those of any other material. It is begin- 

 ning to be largely used in France for fabrics 

 and trimmings in which extreme fineness is 

 not required. 



Fertilization of the Algerian Sahara. 



Some remarkable transformations in the 

 character of the Algerian Sahara have been 

 effected by irrigation. Under its operation 

 a soil has been constituted, in which the 

 intertropical plants grow with great vigor. 

 A cultivator at Ouargla received several 

 medals at the Parisian Exposition for plants 

 which he had raised on a soil thus prepared. 

 The stories that have been told of the pro- 

 ductiveness of the Sahara tax the imagina- 

 tion. Fertility is not limited to any one 

 point. It is exhibited wherever water has 

 been brought to the surface of the soil. 

 Most of the Saharan valleys and the beds 

 of the subterranean streams have water in 

 abundance, and only a small effort is needed 

 to bring it to the surface. Sahara is not all 

 a desert, but contains many considerable 

 tracts which are already fit for cultivation. 

 The success which has attended the efforts 

 so far made to introduce tillage renders it 

 nearly certain that a like reward may be 

 gained from similar applications of labor in 

 other parts. Henceforth it will be safe to 

 say that the transformation of the Sahara is 

 only a question of time, labor, artesian wells, 

 means of communication, and security. 



The Sonrre of Marsh-Odors. M. T. L. 



Fhipson recently read, in the French Acad- 

 emy of Sciences, an account of the sub- 

 stances which he had succeeded in extract- 

 ing from fresh-water algae. They are pal- 

 melline, xanthophyll, chlorophyll, and cha- 

 racine. The last substance receives its name 

 from the odor of ehara, a well-defined 

 marshy smell which it gives out. It is 

 lighter than water, on the surface of which 

 it forms minute pellicles, but is very spar- 



ingly dissolved. It is obtained by first dry- 

 ing the algae in the air, and then covering 

 them again with cold water as in the prep- 

 aration of palmelline. After eight or ten 

 hours, a thin iridescent layer will appear on 

 the surface of the water. This is the odor- 

 ous substance in question. The liquid 

 should be decanted into a long, narrow tube, 

 and shaken with a quantity of ether. The 

 ether dissolves the characine, and leaves it 

 after evaporation in the form of a white, 

 greasy, volatile substance, not saponifiable, 

 soluble in alcohol and ether, hardly soluble 

 in water, and having a strong characteris- 

 tic odor of the marsh, which it communi- 

 cates to the water. After some days it 

 evaporates from the surface of the water, 

 or disappears by oxidation, and the water 

 loses its marshy odor. This odor, so 

 strongly developed in plants of the genus 

 Chara, is due to this new substance, which 

 is formed by the plant itself during its life, 

 and is not a product of decomposition. 

 Characine is found in all the terrestrial 

 algae, and in the confervas. 



A Fossil Ferment. M. Van Tieghem has 

 called attention, in the French Academy of 

 Sciences, to the evidence of the existence 

 of the butyric ferment, bacilns amylobaeter, 

 in the coal period, which has been obtained 

 by the microscopic examination of the rad- 

 icles of conifers that have undergone its 

 action, and are silicified in the phytogenic 

 rocks of Saone-et-Loire. These fossils have 

 been subjected to much study by M. B. 

 Renault, assistant naturalist of the museum. 

 The radicles exhibit precisely the same 

 characteristic marks of alteration as are 

 seen in corresponding radicles of the pres- 

 ent epoch, which have been kept under 

 water, and have become the prey of the 

 bacilus. We know that the effect in the 

 latter case is to subject the cellulose of the 

 radicles to the butyric fermentation; and 

 the conclusion is legitimate that the reac- 

 tions developed in the marshes at the ex- 

 pense of the ligneous matter during the coal 

 period were identical with those from which 

 we observe the same effects now. The im- 

 portance of these observations will be ap- 

 preciated by those who are studying the 

 part which causes that are now in operation 

 have played in the geological past. 



