66 ANNUAL OF SCIENTIFIC DISCOVERY. 



the governor reported it to the home department at Brussels. A commission 

 was appointed two chemists and two botanists who, commencing their 

 inquiry, pursued it carefully for several months, confining themselves to fac- 

 tories in whiclf sulphuric acid, soda, copperas, and chloride of lime were made. 

 The two chemists watched the processes, and noted the escape of gases from 

 the chimneys. They consider soda-factories to be the most noxious, and tall 

 chimneys more hurtful than short ones, because of the greater surface over 

 which they diffuse the vapors; and tall chimneys, by quickening the draught, 

 discharge gases which otherwise would be absorbed in the passage. Hence, 

 contrary to the commonly received opinion in this country, they hold that 

 there is less dispersion of deleterious vapors with a short chimney than a tail 

 one. 



The botanists, on their part, show, as might be anticipated, that the effect 

 on vegetation is most shown in the direction of the prevalent winds, and 

 more during rains and fogs than in clear weather. They establish beyond a 

 doubt the hurtful influence of smoke, due to the presence of hydrochloric 

 and sulphuric acid, and they find that the greatest distance at which the mis- 

 chief is observable is 2000 metres (a little over an English mile); the least, 

 000 metres. They enumerate thirty-four kinds of trees which appear to be 

 most susceptible of harm, beginning with the common hornbeam (Carpi mis 

 Bctuhis), and ending with the alder; and between these two occur, in sequence, 

 beech, sycamore, lime, poplar, apple, rose, and hop. As regards the effect 

 on the health of men and animals, the commission find the proportion of 

 deaths per cent, to be lower now in the surrounding population than before 

 the factories were established : from 1 in 5S it has fallen to 1 in G6. One rea- 

 son for this improvement may consist in the better means of living arising 

 out of the wages earned in the factories. However, the commission wind up 

 their report with an assurance that health, either of men or horses, suffers 

 nothing from the factories, and vegetation so little, that farmers and graziers 

 may dismiss their fears, and the government refrain from interfering. 



SCIENTIFIC VERSUS PRACTICAL INSTRUCTION. 







The following testimony of Liebig as to his famous school at Giessen, is 

 worth considering in these days of schools of practical science. S Hitman's 

 Journal- 



"The technical part of an industrial pursuit can be learned: principles 

 alone can be taught. To learn the trade of husbandry the agriculturist must 

 serve an apprenticeship to it : to inform his mind in the principles of the sci- 

 ence, he must frequent a school specially devoted to this object. It is impos- 

 sible to combine the two; the only practicable way is to take them up succes- 

 sively. I formerly conducted at Giessen a school for practical chemistry, 

 analysis, and other branches connected therewith, and thirty years' experi- 

 ence has taught me that nothing is to be gained by the combination of 

 theoretical with practical instruction. It is only after having gone through 

 a complete course of theoretical instruction in the lecture-hall that the stu- 

 dent can with advantage enter upon the practical part of chemistry. He 

 must bring with him into the laboratory a thorough knowledge of the prin- 

 ciples of the science, or he cannot possibly understand the practical opera- 

 tions. If he is ignorant of these principles, he has no business in the labora- 

 tory. In all industrial pursuits connected with the natural science?, in fact, 

 in all pm-suits not simply dependent on manual dexterity, the dcvelopement 

 of the intellectual faculties by what may be termed school learning, consti- 



