nORTK ULTURAL SOCIETY OF LONDON. 337 



biibly also of sulphuretted hydrogen, which under the ordinary 

 system of exposing manure to the air would be lost. Further 

 experiments on this subject are now in progress. 



An experiment on the influence exerted by the soil on the 

 COLOUR of flowers, though it failed in throwing light on the imme- 

 diate object of experiment, led to some curious and interesting 

 results. Two perfectly similar plants of the Hydrangea were 

 taken and placed under the same general conditions with respect 

 to light, air, etc., and watered with dilute solutions, the one of 

 carbonate of soda, the other of muriatic acid, commencing with 

 very small quantities and gradually increasing the doses. At the 

 beginning of the experiment it was difficult to distinguish the one 

 from the other ; they had both the same number of leaves, were 

 nearly of the same size, and alike in colour and general vigour, 

 being both remarkably healthy plants. The solutions taken 

 consisted of one drachm of concentrated muriatic acid, and one 

 drachm of carbonate of soda, each dissolved in fifty drachms of 

 water • of these at first one drachm diluted with two ounces of 

 water was given to each plant daily, but the dose was gradually 

 increased to twelve drachms of each solution, so that in a month 

 the one had received nearly five drachms of concentrated muriatic 

 acid, and the other plant more than half an ounce of carbonate 

 of soda. Under this mode of treatment both plants continued to 

 thrive and flourish and the blossoms were large and perfect, those 

 formed by the plant treated with muriatic acid being rather 

 the most forward of the two : they were however both of the 

 same colour, nearly blue, although it was believed that had they 

 been left untouched, the blossoms would have been pink. It is 

 evident that the acid would have a tendency to render certain 

 matters in the soil more soluble than others, whilst the carbonate 

 of soda would have an opposite effect j the acid would render 

 lime, magnesia, bases, and metallic-oxides more soluble, whilst the 

 carbonate of soda would facilitate the solution of silica, acids, and 

 organic substances in the soil. The result of these experiments 

 is rather against those views which have been formed respecting 

 the blue and red flowers of the Hydrangea, in which it is supposed 

 that the absorption of iron or lime was essential to the change. 

 During the progress of these experiments two facts worthy of re- 

 cord were observed, the one was that some plants are able to absorb 

 a large quantity of muriatic acid, and secondly that great influ- 

 ence is exerted on the rate of evaporation of tHe leaves, by the 

 substances absorbed from the soil. In most of the hitherto de- 

 scribed experiments on the action of muriatic acid on growing 

 plants, they have been exposed to the gas or vapour, which was 

 found to possess poisonous powers 3 and indeed a great deal has 



