202 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



pidity of ascent of the fluid. Professor Church suggests for 

 this case the use of lithium citrate, a salt easily taken up l^y 

 plants, and one which can be detected with the greatest read- 

 iness by means of the spectroscope. Its advantages consist 

 in its containing an organic acid, and in not being likely to 

 meet with any obstruction to its passage from the tissues. 

 An experiment has lately been made with this liquid, as sug- 

 gested, with great success ; in one instance the fluid having 

 risen nine inches in thirty minutes, in another five and a half 

 inches in ten minutes. This is thought superior to the use of 

 coloring matters, which seemed to experience considerable 

 resistance in their passage through the vessels. 12 A, Octo- 

 ber 27,1870,515. 



IXJURY TO VEGETATION FROM GAS. 



It is by no means an uncommon assumption that illumina- 

 ting gas, in escaping from pipes into the soil, exercises a poi- 

 sonous influence upon vegetation, and a suit was recently 

 brought at Aix-la-Chapelle hj the city authorities against a 

 gas company for recovery of supposed damage to the shade- 

 trees of the city resulting from their careless method of lay- 

 ing the pipes. This was the cause of a detailed series of ex- 

 periments in regard to the assumed fact, and, somewhat to the 

 surprise of every one, it was ascertained that purified illumi- 

 nating gas had really little or no injurious effect of the kind 

 asserted. The experiments were conducted by eminent chem- 

 ists, and included trials with pure hydrogen, light carburet- 

 ed hydrogen, and heavy carbureted hydrogen, as w^ell as pu- 

 rified illuminating gas. A discharge, during an entire day, 

 of these various gaseous substances into the soil of vessels 

 containing growing plants was found to produce little, if any, 

 hurtful result. It was different, however, when these same 

 gases were impregnated with the constituents of coal tar, es- 

 pecially with carbolic acid, in which case, after a few days, a 

 very decided injury to the vegetation was found to have 

 taken place. The effect seemed to be that these impurities, 

 coming in contact with the roots of the plants, deposit tarry 

 matter upon them, which ultimately caused death by a kind 

 of asphyxia. The smallest quantity of carbolic acid was 

 found to have a very decided influence, so that the princi- 

 pal caution to be observed, as far as injurious results are con- 



