This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: …on a watch glass and testing with ferric chloride and ether, gave no red color to the ether. The result was also negative upon evaporating under suction. But when 0.1 cc. iV/100 KSCN solution was added and the saliva then dried under lessened atmospheric pressure, a positive result was obtained. The explanation of these facts seems quite plain. The amount of sulfocyanate present in the salivary secretion was just at the limit of complete dissociation. The amount of KSCN that was added was quite enough to increase the concentration of the thiocyanates and thus allow some of the substance to remain undissociated. The fact, therefore, that frequently we do not get a coloration of the ether when shaken with dried saliva which had been treated with FeCl3 solution is no evidence of the absence of thiocyanates. In fact, according to the light of the dissociation theory, it is somewhat a corroborative evidence of its presence. The absence of the ether coloration is in a way a quantitative test of the amount of the sulfocyanate in the saliva. For it is evident that slight amounts of thiocyanates will give a negative result, while greater quantities will cause a positive reaction. 4. Substances that will give a similar color with ferric chloride, or that may interfere, in general, with the sulfocyanate test. (a) Neutral Formates.1–When a neutral formic salt is treated with dilute ferric chloride, a deep red coloration is produced. This color is still retained when the medium is just acid, i. e., upon addition of a few drops of formic or acetic acid. One or two drops of 10 per cent. HC l may be added without changing the color, but a few drops more of this acid dispels the red hue. I made a solution of the neutral formate which when treated with dilute neutral ferric…
