DISINFECTANTS AND DISINFECTION 349 



The liberated sodium reacts on the water breaking it up into hydrogen and 

 hydroxyl ions to form sodium hydrate. The sodium hydrate in turn com- 

 bines with the chlorine to form sodium hypochlorite, (Na O Cl) which 

 becomes active in the sterilization of the water." 



Pharmacists find considerable demand for distilled water for drinking 

 purposes as well as for use in dispensing. However, some of the leading 

 authorities declare that drinking distilled water is objectionable, because 

 of the disturbance of the osmotic pressure in the cells of the digestive tract. 

 That is, the distilled water acts as a mechanical poison. There is an ex- 

 cessive endosmosis inducing an abnormal distention of the cells, causing 

 physiological disturbances. This action is due to the fact that the mineral 

 salts present in natural drinking water are absent in distilled water. 



The pharmacist can prepare cheaply and simply a marketable drinking 

 water which does not have the objectionable qualities above referred to. 

 Instead of distilling the water, filter it, using a Pasteur-Chamberland filter. 

 Whether a large or small filter is used will depend upon the number of 

 customers to be supplied. In all probability a two- or three-tube filter is 

 large enough for the average retail store.- "Rapid safety filters" are of no 

 value whatever, and should not be used, as they are in no sense germ-proof. 

 They merely remove the . coarse filth. It is true that the Pasteur- 

 Chamberland filters are not absolutely germ-proof, but they remove most 

 of the microbes present, as may be determined bacteriologically by the 

 pharmacist himself. The few germs which may pass through the filter 

 are killed by heating the water to the boiling-point or 30 minutes. Such 

 filtered and heat sterilized water should be sold in large sterile glass or 

 earthenware containers. It is more palatable than distilled water and 

 does not interfere with the osmotic balance of cells. 



5. Food Preservatives 



The use of food preservatives is as old as the history of man. Since 

 remotest antiquity man has found it necessary to accumulate a supply of 

 food during the seasonal periods of plenty in order to tide over the periods 

 of scarcity. The very first observation made was that the accumulated 

 and stored food soon showed a tendency to undergo decomposition. The 

 next observation no doubt was that under certain conditions some organic 

 food kept better than under other conditions, thus, for example, primitive 

 man gradually learned that sun-dried meats did not decompose nearly as 

 quickly as undried meats. No doubt the value of smoking meats was soon 

 ascertained, in all probability purely accidentally, from meats, etc., 

 which had been exposed to the smoke of the camp fire. The preservative 

 value of heat, as in cooking and roasting, was noted. Next, no doubt the 

 preservative properties of certain chemicals used with foods, as ashes 



