158 Proceedings of the Royal Irish Academy. 



powerful poison, and many instances are now on record where it has 

 been the cause of death, such being generally either cases of suicide, 

 or those where it has been accidentally taken by mistake for some other 

 substance ; as its odour and taste would render its administration, at 

 least to an adult, by the assassin for the criminal destruction of life, a 

 matter of some difficulty. The occurrence, however, from time to time 

 of the cases referred to obviously renders it very desirable to be able 

 readily to detect the presence of carbolic acid where it has been so used, 

 either in the articles of food, drink, or medicine which have been 

 taken, or in the ejecta or contents of the stomach ; and this test affords 

 a very easy and ready means of so doing, and of confirming the indica- 

 tions of other tests. According to my observations it will detect the 

 presence of carbolic acid in different complex organic mixtures, even 

 where the odour of that substance may be quite imperceptible ; and I 

 may observe, that the test of odour has hitherto been regarded as the 

 most delicate for carbolic acid in such cases. 



The great advantage this test possesses, especially for such appli- 

 cations, is this, that it does not appear to be much affected or interfered 

 with, as already stated, by the presence of a number of organic sub- 

 stances which are likely to be present in such cases. Thus, as regards 

 different articles of food — I have readily detected, by means of this 

 test, the presence of carbolic acid when a small quantity of its 

 aqueous solution had been added to the following articles, viz. : tea 

 and coff'ee mixed with sugar and milk, porter,^ ale, wine, a solution 

 of Liebig's extract of meat, and albumen ; also where it had been 

 added to blood, olive oil, gum, and soap — the very diverse substances 

 in the articles mentioned not preventing the indications of the test. 



It will also afford a ready means of detecting the elimination of 

 carbolic acid in the urine, when that substance has been taken inter- 

 nally, for the compounds present in human urine naturally do not 

 appear to affect to any extent this test. I may also observe, that 

 with it I was at once able to detect the presence of carbolic 

 acid naturally occurring in the urine of a cow, without any previous 

 treatment of that secretion, and thus confirm the correctness of the 

 statement as to the occurrence of that acid as a normal substance in 

 the urinary secretion of that animal. This ready means of discover- 

 ing carbolic acid in different animal fluids where it may exist will 

 render this test useful to the physiologist and physician. 



- As alcohol acts on the molyhdic sohition producing an intense blue coloui'a- 

 tion, the presence of that substance, at least in any quantity, woiild mask more or 

 less completely the reaction of carbolic acid. In examining, therefore, alcoholic 

 liquors for that acid, it is better to submit them to distillation to separate the 

 alcohol, and then to test the later portions of the distillate or the residue for car- 

 bolic acid ; or what answers even stiU better in such cases is, to render the liquid 

 alkaline by the addition of either caustic potash or soda, to combine with and fix 

 the carbolic acid, and then distil ; and Avhen all the spirit has been removed, to 

 add diluted sulphuric acid to slight acid reaction to liberate the carbolic acid, and 

 after this distil again, when that acid wiU come over unmixed with any spirit, 

 and give its characteristic reaction. 



