FORMALDEHYDE 391 



use does not interfere with its efficacy. It is inhaled, 

 administered on a piece of sugar, or in draught with rectified 

 spirit or ether. Ether, chloral, or full doses of alcohol in- 

 tensify its effects. 



Sodium nitrite, obtained by fusing sodium nitrate with 

 metallic lead, has the same actions as amyl-nitrite, is given 

 in the same doses, and is more stable and convenient. Its 

 effects are not so rapidly produced, but persist longer, often 

 continuing for half an hour. 



Trinitroglyeerin, Nitre-glycerin, or glonoin, C 3 H 5 (N0 3 ) 3 

 is prepared by dropping pure glycerin into a mixture of sul- 

 phuric and nitric acids kept cool by ice, and washing it in 

 water. Specific gravity, 1*6. It is a colourless, transparent, 

 explosive liquid, soluble in alcohol, ether, and oils. Its 

 actions resemble those of amyl and sodium nitrites, but are 

 more powerful and persistent, while full doses affect the 

 voluntary as well as the involuntary muscles. It is used 

 for the same purposes as amyl-nitrite. The preparation 

 generally preferred is the B.P. alcoholic solution, liquor 

 trinitrini, of which 110 minims contain one grain of nitro- 

 glycerin. The dose for human patients is a half to two 

 minims. For dogs suffering from spasmodic asthma or 

 epilepsy, a teaspoonful of a solution of 1T\30 of liquor 

 trinitrini in ten ounces of water may be given as required. 

 Chocolate tablets containing one-hundredth of a grain 

 of nitroglycerin are now obtainable. 



FORMALDEHYDE-FORMALIN 



Formaldehyde (H.COH) is a gaseous body obtained by 

 subjecting methyl alcohol to oxidation. It is a very power- 

 ful disinfectant and germicide. A concentrated (35 to 40 

 per cent.), aqueous solution is known as formalin, or Formol, 

 a colourless liquid, with a strong, pungent odour and neutral 

 reaction, which is largely used as a disinfectant, deodorant, 

 and preservative in solutions of from one to five per cent. 

 Formalin is stated -to retard the healing of surgical wounds. 

 Undiluted it is irritant and caustic to tissues, and corrosive 

 to surgical instruments. Strong solutions applied to the 

 skin may induce poisoning. A solution of one in five 



