62 



laboratory for consideratiou. The results of some x)relimiiiary inves- 

 tigations have proved of such interest as to warrant immediate 

 publication. 



CREOSOTE BUSH. 



/ A specimen of the creosote bush ^ ( Co villea tridentata) was examined. 



'' This, while a desert plant, is said to stiun~soiis where there is much 

 water-soluble salts. Mr. Means states that its presence can be taken 

 as a sure indication of land free from injurious quantities of alkali. 

 It is found in dr}", well-drained upland soils. 



The material was thoroughly air dried. The leaves and stems were 

 then carefully separated, and both of the separated samples were 

 ground fine in an agate mortar. A portion of each sample was burned 

 to ash. The finel}^ ground air-dried material and the ash were each 

 carefully leached with successiA^e small portions of water until the 

 leachings ceased to show the presence of chlorides. The leachings in 

 each case were then brought together and made up to a volume of 500 

 cubic centimeters, and the various determinations were made with 

 100 cubic centimeter portions. The carbonates^ were determined 

 by titrating with a twentieth normal (X 20) solution of hydrogen 

 potassium sulpliate until loss of color, using phenolphthaleine as indi- 

 cator. So soon as the color had disappeared a drop or two of a solu- 

 tion of potassium chromate was added and the chlorine determined 

 b}^ titrating with a tenth normal (X, 10) solution of silver nitrate. 

 The sulphates, when determined, were estimated gravimetrically as 

 barium sulphate in the usual manner. For convenience the acids thus 

 found to be present are stated as the corresponding sodium salts. 

 This procedure seemed to be justified by a subsequent determination 

 of the amount of sodium present in the solution. It is a well estab- 

 lished fact, and a familiar one to chemists, that when a salt of an 

 alkali metal is burned down with charcoal or other organic matter a 

 part of the mineral acid is volatilized and driven oif , the alkali base 

 forming a carbonate, which is a stable compound even at quite high 

 temperatures. Nevertheless this is a point often overlooked in the 

 discussion of ash analyses. In obtaining the ashes the examinations 

 of which are described in this i^aper, very great care was exercised to 

 reduce the amount of tliis loss of the mineral acid as far as possible, 

 and the burning was done at as low 'a temperature as possible. In 

 some cases the large amount of fused salt in the burning ash coated 

 the charred organic matter in such a way as to render furtlier com- 

 bustion at a comparatively low temperature quite impossible. In these 

 cases the combustion was. stopped, the fused salts leached out with 

 water, and the residue reburned. It seems probable, as will appear 

 from the results which \vill be presented, that the loss of mineral acids 



^Collected by Mr. Thos. H. Means near Tempe, Ariz.; kindly identified for us 

 by Mr. F. V. Coville. 



'Report 64, Division of Soils, U. S. Dept. Agr. (1900); Amer. Chem. Jour., 23, 

 571 (1900) . Bui. 18, p. 77, Division of Soils, U. S. Department of Agriculture (1901) . 



