510 



•watered a plot of ground of 100 square feet, contaiuing young barley, 

 with a solution of arsenious acid in the proportion of two ounces per 

 ten gallons of water, and after six days the crop had a blighted appear- 

 ance. A similar jjlot was then watered with a solution of half this 

 strength, and after two applications at an interval of twelve days, this 

 crop also appeared to be injured. The treatment was, however, again 

 continued after a short time, so that in all five applications were made, 

 yet the crop matured. 



A similar plot sown with turnips received applications amounting to 

 4 ounces arsenious acid per 100 square feet, and were in no wise injured. 

 In case of the barley the indications of arsenic shown by the Marsh 

 test were very slight, and in case of tests made both by the author and 

 by Professor Brodie decidedly negative results were given. 



It will therefore be seen that the general character of the results 

 which have been obtained from investigations upon this subject has in 

 the main been negative. 



Having thus given the results of our preliminary experiments and the 

 history of the matter, so far as we have been able to obtain it, we shall 

 continue our investigations in this regard and i)ublish the results from 

 time to time as they may be obtained. 



Aluminium m plants. — It is well known that alumina is seldom if 

 ever present in the ashes of the phoenogams; but since 1853, when the fact 

 was determined by Eitthausen, its presence in the cryptogams has been 

 generally admitted. Prof. A. H. Church has furnished evidences of this 

 fact in the results of his late researches upon plants of this class, as ex- 

 hibited in the following table : 



One hundred parts of 

 ash contain — 



Silica. 



Alumina. 



Lycopodium alpinum 



L. Clavatum 



L. Selago 



Selagiuellam artensii 



Selagiuella spinulosa . 



Equisetum maximum 



Ophiaglossum vulgatum. 

 Psilotura triquetrnm 



10.24 

 6.40 

 2.53 



41.03 

 6.67 



62.95 

 5.32 

 3.77 



33.50 

 15.24 



7.29 



0.26 



None 



None 



None 



Trace (?) 



SuLPHOCYANic ACID POISONOUS TO PLANTS. — The poisonous and cor- 

 rosive action upon plants, lately attributed by Euroj)ean agriculturists 

 to phosphoric acid, has been found to be due rather to the sulphocyanic 

 acid existing in the crude sulphate of ammonia obtained as a by-product 

 in the manufacture of coal-gas, and employed in the manufacture of 

 superphosphates. This sulphate of ammonia often contains consider- 

 able quantities of sulphocyanide of ammonium, which, according to cer- 

 tain German investigators, exerts a decidedly poisonous influence upon 

 vegetation. Since, therefore, it is advisable that the commercial sul- 

 phate of ammonia used for agricultural i^urposes should be free from 

 this compound, it should be previously examined by testing with salts 

 of the peroxide of iron, which indicates its presence by the appearance 

 of a red coloration. 

 - What is an AMELioPtATiNG CULTURE ? — This subject has been ably 



