No. XXI.] APPENDIX. 293 



chrysalis finally lose its case and become the beautiful butterfly. This 

 forms a palpable series of changes, the order of which your memory is 

 not likely to alter ; but changes continually occur in all bodies, and these 

 changes you must be very careful to note in the order in which they occur. 



In chemistry the transmutations of matter under various circum- 

 stances are of the most extraordinary character. The beautiful pigment 

 called Prussian-blue is but a change of offensive animal matter, potash 

 and iron. Some of our scents and flavours also, as the oil of pine-apple 

 and the oil of the delicious ribstone pippin, are the products of chemical 

 changes from, fusel oil, a most offensive product in the distillation of 

 spirit. In acquiring a knowledge of these changes, the educational 

 lectures at the London Institution will be of great service to you. We 

 have a laboratory with all necessary materials, and every form of apparatus 

 is at our command, which may be required to illustrate the different 

 subjects. A lecture would frequently cost a large sum of money, were 

 .not the apparatus at hand, or could it not be easily borrowed. It is for 

 this reason that ordinary schools cannot undertake the teaching of these 

 subjects : and were I to tell you of the labour and expense required for 

 some of the lectures which have been delivered within these walls, you 

 would be especially thankful for the privilege which you possess of being 

 enabled to attend these demonstrations. 



The knowledge which here will be brought before you will be of the 

 utmost value in future life. Each fact may be regarded as a unit of 

 knowledge ; and those who acquire the most will have a great advantage 

 over their fellows. I show you a piece of gossan, a peculiar sort of stone 

 which guides the miner to the detection of copper ore, and large fortunes 

 have been made by a knowledge of the peculiarities of the stone. This is 

 a simple mineralogical fact, but I might illustrate similar facts in every 

 department of science. 



It is not, however, a mere question of utility, but there is the highest 

 gratification also to be found in a careful observance of Nature, and the 

 study of Nature's laws. A touching anecdote was told me by Mr. Spence, 

 the distinguished author of the work on Entomology, which I commend to 

 the notice of you all. At the Model Prison a person was confined in a 

 dismal cell, with windows "which did not allow him ever to see the sky. 

 When he took exercise, he paced a few square yards in the same spot day 

 by day. His only amusement under this terrible sentence was minutely 

 ,to notice every little weed which grew upon it. He saw these sprout from 

 seed, increase in growth, bud, flower, and seed again. Now, when I tell 

 you that the plants so observed were simply the shepherd's-purse, the 

 groundsel, and a few more weeds, you will see how great is your advantage, 

 when you consider the multitude of plants which clothe the earth, the 

 countless swarms of insects which fly in the air, the fish, the birds, the 

 animals, the changes of the seasons, and even the works of men's hands 

 which are open to your observation in freedom. In fact everything which 

 .is contained upon the earth and even in the firmament of heaven, the sun, 

 the moon, the planets, the comets, the stars, the nebulae, will afford you 

 objects for observation, study, and delight, if you will only regard them 

 with intelligence and attention. There is in fact no end to the acquisition 

 of natural knowledge : for if you could know all which others have dis- 

 -covcred, it would be but as a drop of water to the ocean. The study of 



