It is uncertain what the Naxian whetstone was, but it was considered the best variety of whetstone. It is mentioned in Pindar. From the fact that emery is found in Naxos one might conclude that the Naxian whetstone was of emery, but a few lines before the passage quoted from Paul he has already mentioned the emery: Ἡ δὲ σμύρις ῥυπτικὴν ἔχουσα δύναμιν ὀδόντας σμήχει. 'The emery having detergent powers cleanses teeth.' Galen makes the Naxian stone a variety of ostracites which was apparently marble formed of shells. One of the marble ointment tablets had, we saw, been used as a whetstone, but the whetstones for which Naxos was famous must, if not emery, have been some variety of shale or slate. It seems contrasted to some extent with the 'oilstone', i. e. whetstone which required oil. This was a clay slate (see Pliny, _H. N._ xxxvi. 47). There are several whetstones from Stabiae in the Naples Museum which are classed among surgical implements. Whetstones are common objects in the finds from any Roman settlement, but they are not ground to regular shapes as our whetstones are. They usually consist of fine sandy schistaceous shale. CHAPTER XI ÉTUI, ETC. _Portable Outfit._ After describing the larger apparatus necessary for the equipment of the surgery, Hippocrates mentions a portable equipment for use on journeys: 'Have also another apparatus ready to hand for journeys, simply prepared, and handy too by method of arrangement, for one cannot overhaul everything' (i. 72). The component parts of this portable outfit so far known to us are as follows: The scalpels of different shapes seem to have been carried in boxes, probably wooden, which opened in two halves like a modern mathematical instrument box. In these the scalpels lay head and tail, separated from each other by small fixed partitions. A box of scalpels of this kind is represented in a marble votive tablet which was found on the Acropolis on the site of the Temple of Aesculapius. A similar box with different instruments is seen in a donarium in the Capitoline Museum. The probes and forceps were carried in cylindrical cases like those in which the scribes carried their pens. A good many of these have come down to us. From the fact that in the grave of the surgeon of Paris there were found two buckles, it is probable that there had been buried along with the instruments a case of leather or some such perishable material, which had been used to contain instruments, but which had disappeared when the grave was opened. There have also been found boxes of various shapes for containing medicaments, cylindrical boxes for drugs in sticks, boxes divided into little partitions for drugs in semi-solid form, and other boxes for powders. _Portable Probe Cases._