2IO 



SCIENTIFIC NEWS. 



[Nov. 1st, 1887. 



and probably in all, infectious diseases, the action exerted by 

 living organisms on chemical compounds is the all-important 

 factor. It is chiefly to the brilliant researches of Pasteur that 

 we are indebted for the proof that the processes of fermentation 

 and putrefaction are due to the action of minute living organisms, 

 while Koch and others have indicated the import and part which 

 these lower forms of life play in the case ol many diseases both 

 in man and animals. 



MICRO-ORGANISMS NOT THE CAUSE OF DISEASE. 



The latest researches, however, have, shown that the direct 

 cause of an infectious disease is not the micro-organism himself, 

 but that it is due to the poisonous effects of the compounds re- 

 sulting from the chemical action of the micro-organisms on the 

 tissues or fluids of the body. An infectious disease is due, there- 

 fore, to the products formed by the micro-organism rather than 

 to the organism itself, for it has quite recently been shown that 

 the disease can be communicated by such poisons in the entire 

 absence of living organisms. The compounds produced by living 

 ferments, and indeed by all micro-organisms, usually act as 

 poisons to these ferments, so that if the products accumulate 

 beyond a certain extent they kill the ferments. This is exactly 

 analogous to the higher animals and to man. One of the most 

 important products of animal life is the carbonic acid produced 

 by respiration, and we know that if this carbonic acid be allowed 

 to accumulate beyond a certain amount the animal soon dies. In 

 this way the yeast plant, when living in a solution of sugar, is 

 killed by the alcohol it produces as soon as the proportion of the 

 latter amounts to 20 per cent. 



THE ART OF BREWING. 



Though the art of brewing has been known for at least 2,000 

 years, and though the manufacture of wine was carried on so 

 early as the time of Noah, yet nothing was really known as to 

 the modus operandi of the production of beer and wine. The 

 brewer and wine-grower learnt from long experience the con- 

 ditions but not the reasons of success. No man, in fact, knew 

 the secret of their formation. It is to the splendid genius of 

 Pasteur that we chiefly owe our present knowledge of the real 

 agents in fermentation. He has shown that grape juice ferments 

 in virtue of the action of a minute micro-organism which at the 

 time of vintage is found adhering as a parasite to the outside of 

 the grapes and the adjacent t^vigs, and that yeast induces the 

 fermentation in brewing in virtue of its being a living organism ; 

 and that in each case the resulting alcohol is a product of the 

 growth of these micro-organisms, just as carbonic acid is the 

 product of the life of man and the higher animals, or as india- 

 rubber is a product of a special kind of plant. The brewer is a 

 kind of farmer. But whereas the farmer sows his corn to get 

 more corn, the brewer sows his yeast to produce certain chemi- 

 cal changes in the wort, resulting in the formation of alcohol and 

 the production of beer. In this connection it is interesting to 

 think that the yeast used by the brewer to-day is the lineal 

 descendant of the yeast used by brewers more than two thousand 

 years ago. 



PUTREFACTION. 



Until quite recently the putrefaction of animal and vegetable 

 matters was thought to be entirely a process of oxidation, and, 

 in this respect, to be strictly analogous to the rusting of iron and 

 in the atmospheric corrosion of other metals. But it has been 

 conclusively shown that pure air, even in the presence of mois- 

 ture, is quite incapable of producing putrefaction, and that the 

 presence of living organisms is absolutely necessary for inducing 

 putrefactive changes. It seems that the chemical action of these 

 micro-organisms is somewhat similar to what takes place during 

 ordinary digestion. The micro-organisms abstract the elements 

 they require, and the remainder react on one another to form 

 nev,' combinations. In the process of decomposition certain 

 products are formed, called ptomaines, which are closely allied 

 to strychnine, morphine, etc., and are frightful poisons. The 

 poisonous properties of various kinds of food which have under- 

 gone putrefaction are due to the presence of these ptomaines, 

 resulting from the action of the putrefactive micro-organisms! 

 This has been the case with several well-known instances of 

 sausage-poisoning, poisoning by bad fish, and even with mouldy 

 Dread. The formation of these ptomaines during disease or after 

 death has a most important bearing upon the treatment of cases 

 of suspected poisoning in criminal trials, inasmuch as whether 

 poisonous or not their reactions differ very little from those of 



the deadly alkaloids ; and in the interests of justice it is to be 

 hoped that our knowledge of this branch of organic chemistry 

 may soon be rendered as complete as possible. 



THE LESSON OF BIO-CHEMISTRY. 



Bio-chemistry, and especially that part of it dealing with 

 micro-organisms, teaches us at least one lesson, and a lesson, 

 too, which is in unison with that taught by nature generally, viz., 

 that the great things and phenomena of the world and of the 

 universe are accomplished by apparently insignificant, and, at 

 first sight, insulKcient means. Were the larger animals, such as 

 the great carnivora, annihilated, the world would not be very 

 different from what it is. Annihilate, however, the almost infi- 

 nitesimally minute micro-organisms of fermentation and putre- 

 faction, and the result would be a total revolution as regards the 

 life of the world. What is it that strikes the greatest terror to 

 the heart of man ? It is not the tramp of armed men led by a 

 Hannibal, a Caesar, or a Napoleon, nor the howling of beasts of 

 prey. It is the silent march of a dread disease, of the inconceiv- 

 ably minute organisms of cholera, of small-pox, of consumption, 

 or other like scourges of the human race. Pure and moteless 

 air gives perfect immunity from putrefaction and disease, but 

 consider the dread effects which have followed the course of air 

 charged with the germs of an infectious disease ; of what sor- 

 row, what sickness and death has it been the cause in ages past. 

 Even the terrors of the battlefield itself often sink into insignifi- 

 cance by the side of the ravages occasioned by the sickness and 

 disease resulting from the putrefactive micro-organisms of the 

 air, let loose on the living and the slain. It is no exaggeration 

 to say that micro-organisms wafted in the air have been the 

 cause of greater calamities than all the wars, earthquakes, 

 famines, and the like put together. 



NORTH OF ENGLAND INSTITUTE OF MINING AND 

 MECHANICAL ENGINEERS. 



Abridgment of the Presidential Address of Sir Lowthian 

 Bell, F.R.S. — contimted. 



The numbers just quoted indicate with sufficient clearness how 

 largely modern navigation is indebted to coal for the immense 

 strides it has made in recent years, and although its dependence 

 on the use of iron may not be so obvious, we are all aware that wood 

 is now but very sparingly employed in naval architecture. Indeed 

 its use may be said to be confined to forming the deck and lining 

 the cabins of our ships. Let us now briefly consider what has 

 been done in order to connect continents with each other by sea, 

 in a manner more consistent with what the locomotive had 

 achieved in uniting districts and nations by land than could have 

 been accomplished by wooden ships depending on the wind for 

 motion. 



In our Exhibition there maybe seen a very beautiful model 

 showing the design of a steam engine estimated to work to 

 nearly 25,000 indicated horse power, about to be constructed on 

 the Tyne for an Italian ship of war. We also know that ocean- 

 going steamers of very large dimensions have been built capable 

 of running 25 miles in the hour — a speed equal to that of our 

 best trains 50 years ago. The strain imparted to the hull of a 

 vessel under such trying circumstances as those just mentioned, 

 makes it more than doubtful whether it would have been possible 

 to obtain the necessary strength with wood, forming as it were 

 a hollow foundation of a comparatively weak material, to con- 

 nect these tremendous forces with their work. If this view be 

 correct in principle, the adaptation of iron for the frames and 

 planking of our ships is a very important factor in the enormous 

 development of steam navigation. It may be questioned whether, 

 at the commencement of the reign of Queen Victoria, there was 

 a single sea-going vessel of iron afloat. Thirteen years after 

 Her Majesty ascended the throne there was built in the United 

 Kingdom 132,800 tons of shipping, of which 12,800 tons only 

 were of iron. In 1883 we launched in this Kingdom 1,116,555 

 tons, that is, more that eight times the amount built in 1850; 

 and of this 16,353 t°ns only were of wood, and the remainder of 

 iron. I am not aware of the exact number of iron vessels now 

 in existence, but I have estimated that in the seven years ending 

 1884, close on 4,000,000 tons of iron and steel had been con- 

 sumed in hulls and engines by our shipbuilders. Of this weight 

 about 763,000 tons were used in 1882, followed by about 860,000 

 tons in the year 1884. 



