ATOMIC WEIGHTS. 



CHAPTER VI. 

 THE COMBINATIONS OF ORGANIC SUBSTANCES. 



It is one of the grand laws of nature, that however often 

 matter may change its form, it is never lost. Matter is in- 

 destructible. It is changed and rechanged into infinitely 

 numerous and varied forms, but it never loses a particle and 

 there is no waste. Another universal law is that "of noth- 

 ing, nothing only comes," and that mankind with all their 

 work and labor can expect nothing more from the soil or 

 from any natural element than it contains. Labor only, 

 changes the forpi of matter; it never creates anything. 

 Another grand law of nature is that all matter of whatever 

 kind, exists in the form of very minute particles, which are 

 so small as to be invisible; that these are unchangeable; 

 and that as the various elementary substances combine with 

 each other, they invariably do so in precisely the same pro- 

 portions. Thus 8 atoms or particles, (or pounds ; the quan- 

 tity makes no difference) of oxygen, and 1 part by weight 

 of hydrogen, combine to make water ; that potash consists 

 ever and always of 39 parts of potassium and 8 of oxygen ; 

 and common salt of 35 parts of chlorine to 23 of sodium ; 

 and so on through the whole list of the 65 known elemen- 

 tary substances. Certain numbers, known by long contin- 

 ued experiment, and called combining numbers, or atomic 

 weights, represent the proportions, by weight, in which the 

 elements unite to form all their compounds. A compound 

 is not a mixture. If we take salt and sand and mix them 

 together, no matter how intimately, the salt remains the 

 same and so does the sand, and they can be separated by 

 adding water which will dissolve the salt and leave the sand 

 as it was before. The salt and water are also mixed and 

 can be separated by boiling away the water and leaving tho 

 salt dry. The water may be converted into steam or vapor; 



