222 Application of Charcoal to the Gro'wth of Plants. 



communicating my experience on the subject. My experiments 

 are not numerous, and I should have considered them too trifling 

 when compared with those of M. Lucas, if in one important 

 respect they had not proved the very contrary of his, namely, 

 with respect to the number of roots. 



In the year 18311 made several experiments to cause Pri- 

 mula prae'nitens to produce blue flowers, as is frequently the case 

 with Hydrangea hortensis. After several unsuccessful attempts 

 I had recourse to charcoal earth, such as is frequently found in 

 woods where charcoal has been burnt. I took a plant of Pri- 

 mula prae'nitens about two or three months old, with a very 

 small ball of earth to the roots, and planted it in charcoal earth, 

 where it grew luxuriantly, but instead of the flowers being blue 

 they were of a bright red. A friend, who was interested in my 

 experiments, thought the cause of my failure in this instance 

 was owing to the plants having a ball of earth when planted, on 

 which account the charcoal could not take proper effect. To 

 ascertain if this were the case, I took some pure charcoal ashes, 

 and planted a cutting of P. prse'nitens in it, which grew in a short 

 time, and produced many beautiful red flowers. As I use very 

 small pots for my experiments, on account of want of room, I 

 am soon obliged to transplant my cuttings ; after a full quarter of 

 a year I took the primulas out of the pots to transplant them, 

 but I found, to my astonishment, very few roots, and I therefore 

 replanted them in their old pots, in which they remained from 

 spring 1832 to spring 1833. When transplanting my other 

 primulas in spring 1833, I also transplanted these, and found 

 that, after being in the charcoal ashes a year and a half, they had 

 not made so many roots as the others, which had only been 

 planted half a year in common earth. 



To examine the roots more closely, I shook away the whole 

 ball, and found that the plant had three main roots, which were 

 furnished with fine fibres and spongioles, and from the stem to 

 the point were of a bright red colour, like the flowers. 



This discovery was of great importance to me, as, by this 

 treatment, frequent transplanting and the use of large pots were 

 obviated. From this time I planted my primulas in charcoal 

 ashes mixed with one half sandy bog earth, in small pots, in 

 which they grew well, and produced abundance of flowers. The 

 cuttings grown in 1832, in charcoal ashes, are still alive, and 

 have stems \\ ft. high, which have always fine crowns of leaves 

 and flowers. I transplant these plants every autunm, always in 

 the same 2-inch pots, take away the half of the ball of roots, 

 and any side shoots that are beginning to appear, and keep them 

 tolerably moist. 



These favourable results induced me to mix charcoal with 

 earth for various plants, and I always found that the plants were 



