96 The Ottawa Naturalist. 



has been a grievous disappointment. I find the lectures to be a 

 concentrated digest of the technical application of chemical — 

 and other— principles, such as one finds and expects to find in 

 treatises on such subjects. No one who possesses a copy 

 of Wagner's Chemical Technology, or other work of a similar 

 k'r.d, need refer to the text of Professor Lassar-Cohn's lectures. 

 C ):itrariwise, however, it must not be supposed that these 

 lectures take the place of an extended treatise ; for they are 

 necessarily a mere skimming of the surface of so vast a subject 

 Much better trust to a volume of Cooley's Receipts or Spon's 

 very valuable Encyclopaedic work. 



Let it not, however, be imagined that I hold the learned 

 professor in the very least to blame. He has performed, and 

 very well performed, the task he set himself Every reader of 

 this work will learn, in a general way, the modus operandi of the 

 manufacture of soap, sugar, leather, starch, shoeblacking and 

 ten thousand other things— and that is something, is is not? 

 Whether the language, simple as the author has tried to make 

 it, will' convey any clear meaning to him, is often doubtful ; as, 

 for example, where he is told that cellulose and starch resemble 

 each other chemically, in each having a molecule of 21 atoms, 

 6 of carbon, 10 of hydrogen, and 5 of oxygen, and that by the 

 addition of two more atoms of hydrogen and one of oxygen — 

 the equivalent of one molecule of water — the Starch molecule is 

 changed into a molecule of glucose. He is much more likely 

 to remember the bare fact that by boiling starch with an acid it 

 is turned into glucose ; a fact, the knowledge of which to him 

 is of no use for manufacturing purposes, unless he adds to it a 

 hundred others, regarding details of manufacture, which he can 

 only learn by a long apprenticeship to the business, or by years 

 of experiment at his own cost ; a fact, morever, which I hold, is 

 of no more value to him as a thinking human being, than that 

 ethyl alcohol boils at 174° F. under normal conditions of tempera- 

 ture and pressure. 



