A second expedient for the subduing of taste is fat covering, which consists of triturating the drug with liquid petrolatum or other fat, e. g., Crisco in ether, and permitting the ether to evaporate. The thin film of fat left on the drug delays its solution to a slight degree, yet sufficiently to reduce the taste, so that certain drugs--such as aspirin, digitalis, diuretin--can be administered in the form of sweet tablets in useful dose. In these cases, saccharinization and fat covering combined give the best results. * * * * * Most of the alkaloids can be administered in candy form by saccharinization with or without additional fat covering, and, in the case of some, the addition of sodium bicarbonate is still further useful in lessening the solubility, thereby subduing the taste. Only in the case of the bitterest alkaloids such as strychnine and of alkaloids that have to be given in large doses such as quinine are different expedients necessary. For quinine, aristochin or saloquinine solve the problem. For strychnine, Lloyd's "Alcresta" strychnine gives good results. In 1910, John Uri Lloyd[9] of Cincinnati discovered that the addition of fuller's earth to alkaloids almost completely abolished their bitter taste. He found on further research that this activity resided in the finest particles, especially those of colloidal dimensions, which could be separated from the coarser portion of fuller's earth by elutriation. By means of this powder, now known as Lloyd's Reagent, it is possible to obtain the bitterest alkaloids, even strychnine, in almost tasteless form. That this strychnine combination is still active, can be proved by the fact that it will kill a dog almost as readily as the uncombined strychnine. Lloyd has coined the name "Alcresta" for these alkaloidal combinations; they are marketed by Ely Lilly and Company. The combination of the strychnine with fuller's earth is destroyed by alkali and by alcohol. Hence alcohol must not be added to the powder after the Alcresta combination has been incorporated. The addition of a little acid lessens the bitterness of the combination by lessening solubility in the mouth. The addition of acid is also of advantage to lessen the solubility in the saliva, and with it the taste, of such resinous bodies as the resin of podophyllum. Choice of Color. To indicate tablets containing poisonous substances, a dark red color is chosen, unless cacao disguises the taste better. It would be advisable not to prescribe more than a small number of such tablets to be dispensed at one time, so as to prevent the possibility of poisoning. The choice of the other colors has been more or less without special principle underlying it, yellow having been chosen for lemon, and green for wintergreen, leaving pink for rose and white for peppermint. The relation of color to flavor can, of course, be varied. CHAPTER VII. FORMULAE FOR THE PREPARATION OF SWEET TABLETS