INTRODUCTION. xxi 



a draught and thorough ventilation, is required ; or preferably a 

 table outside the window in the open air, so that whilst a supply 

 of gas can be led to the table by a short length of flexible tubing 

 in order to obtain heat when required, the evolved vapours, &c., 

 may not become a source of inconvenience or damage inside the 

 house. Wherever liquids of a corrosive nature are employed, such 

 as sulphuric acid (either pure or diluted with water), the same 

 kind of precaution is desirable to avoid damage to furniture by 

 the " accidents " that will inevitably occur with beginners by 

 breakages of various sorts, and upsets ; for similar reasons an old 

 suit of clothes is to be recommended for wear whilst experiment- 

 ing, more especially with chemicals. One of the advantages, and 

 not the least of them, to be gained by making physical and 

 chemical observations and experiments is, that a considerable 

 degree of manual dexterity in arranging and handling apparatus, 

 sometimes of a somewhat fragile character, is gradually cultivated 

 and acquired; the tyro, at first awkward at manipulating un- 

 familiar objects, soon becomes more expert, especially if he 

 endeavours to form the habit of doing everything as carefully 

 and neatly as possible ; the importance in after life of the early 

 cultivation of such a habit, and of the acquisition of manual 

 dexterity and the free " use of the hands and fingers " without 

 awkwardness, can hardly be overestimated, these being of very 

 great advantage in all cases, and simply invaluable in a large 

 variety of professions and special callings. 



C. R. ALDER WRIGHT. 



CHEMICAL LABORATORY, 



ST MARY'S HOSPITAL MEDICAL SCHOOL, 



LONDON, W. 



