CHEMICAL SCIENCE. 219 



Every water-closet, in my opinion, ought to be furnished with a 

 subsidiary pipe branching off from the main pipe, a little below the 

 valve of the closet. This subsidiary pipe should be carried a few 

 feet above the seat of the closet, and its extremity which should 

 be open, with the exception of a few wires stretched across it, merely 

 to prevent the charcoal falling into it should terminate in a char- 

 coal filter six or eight inches thick, into which it should penetrate to 

 the depth of two or three inches, so as, in fact, to be enclosed by a 

 good body of charcoal. Under such an arrangement as this, no foul 

 gases can penetrate into the closet. 



From the preceding statements, it is plain that the oxygen con- 

 tained in the air of the atmosphere is by far the cheapest and most 

 effective deodorizing and disinfecting agent with which we are ac- 

 quainted, and that the usefulness of the charcoal air-filter consists in 

 its affording a safe and advantageous means of applying atmospheric 

 air to disinfecting purposes. 



UNWHOLESOME FOOD. 



Animal poisons still constitute one of the most obscure problems 

 with which chemistry and physiology have to deal. When the Tsetze 

 fly, mentioned by Dr. Livingstone, kills his victim, the horse, by a 

 wasting disease, how small in quantity must be the morbific matter, 

 which, working we know not how, deranges the vital processes of 

 nutrition and assimilation, and modifies the condition of all the fluids 

 in the great body of the unhappy brute. When a German village 

 suffers from the influence of the peculiar virus developed in badly- 

 prepared sausages, or when a dish of mussels torments the admirers 

 of that questionable variety of molluscous food, our analysts fail in 

 their efforts to separate the peccant matter from the general mass, 

 and our physicians are not more successful in the endeavor to explain 

 the precise mode in which disease or death may supervene. We look 

 to the general law that " a molecule in motion tends to communicate 

 similar motions to other molecules within its influence," as expressing 

 what probably takes place in the class of facts with which we have to 

 deal ; and although we may in some cases be able to discriminate be- 

 tween the varying amount of danger attending different stages of 

 putrefaction, we cannot define the precise conditions in which a decay- 

 ing substance exists when it is invested with the highest amount of 

 deleterious power. Offensiveness to the sense of smell is no r criterion, 

 because sulphuretted hydrogen, and other gases, which make a vio- 

 lently unpleasant appeal to our olfactory nerves, are capable of exist- 

 ing quite independent of any organic poison, or miasma, which may 

 or may not accompany them, according to the circumstances of the 

 case. 



When we have to deal with a preparation of arsenic, tobacco, 

 opium, or any substance employed in medicine or the arts, we are 

 able to extract a definite material which has little or no tendency to 

 undergo further change, unless it is brought into contact with other 

 bodies under certain conditions. Thus arsenious acid may be pre- 

 served unaltered for an indefinite period ; the oil of tobacco or 

 the alkaloids of opium will remain unchanged in our bottles ; but 



