SCIENCE-GOSSIF. 



lOI 



The time required for this process depends upon 

 the size of the skull and the temperature of the 

 atmosphere. In hot weather a dog's skull may 

 be clean in a fortnight ; in cold weather three or 

 four months may be required. I have had skulls 

 frozen for months without injury ; indeed, I 

 think freezing them is more likely to benefit the 

 process. 



When no more flesh or ligament can be removed 

 the skull should be washed in water with chloride 

 of lime, the amount of which is not a fixed quan- 

 tity, and must vary according to the size of the 

 skull. As a rough rule, a dessertspoonful of 

 chloride of lime is enough for a pint of water to 

 wash a fox's or badger's skull. The lime should be 

 well pounded before mixing with water, and about 

 ten minutes is long enough for the lime to eat 

 away any particles of ligament or flesh that may 

 remain. The skull when taken out should be well 

 washed under a running tap, and brushed with as 

 hard a brush as can be used without breaking the - 

 small processes protruding from some parts of the 

 skull. Very delicate skulls, as those of the shrews 

 and bats, should never be touched with lime, which 

 soon eats them through. They should, however, be 

 clipped clean with scissors whilst under water, 

 when the small portions of remaining ligament 

 stand out from the skull like fluff. 



When the specimen is finished, it should be 

 placed to dry in the sun. The test of a perfect 

 specimen is the absence of anything like ligament, 

 which shows yellow when viewed under a lens. 



" Natural " Skeletons. 



To set up an entire skeleton, of course, requires 

 more labour. The bones of a large animal are 

 usually all separated and cleaned apart by the pro- 

 cess already mentioned, and finally wired together. 

 With small animals it is much less tedious to make 

 what is termed a " natural " skeleton — i.e. by 

 macerating the whole skeleton together, removing 

 only the skull, taking care that it is not left long 

 enough in water for the ligaments to give way. 

 After the final wash in a little lime the skeleton is 

 propped up by pieces of wood and card, and left to 

 dry in the position required. The ligaments will 

 harden and shrink so as to be quite unnoticeable. 

 When the skeleton is dry it will stand by itself 

 without the aid of any props. Should a ligament 

 give way during maceration, or, later, on setting up 

 the specimen, a touch of diamond cement, fish glue, 

 or gum tragacanth will make a perfect adhesion. 



Affixing the Skull. 

 In the case of small animals like mice or 

 weasels, a slight touch of the above-mentioned 

 adhesives will be sufficient for this purpose ; but 

 with larger specimens, such as dogs, hares, and 

 others, a plug of cork smeared with the adhesive 

 should be inserted into the foramen magnum and 

 also down the tube formed by the cervicals. The 



lower jaws of small animals can be affixed with 

 adhesive, and the jaws of larger animals kept in 

 place by a ligature of slender wire. It is preferable 

 in all cases where the whole skeleton is not set up 

 to keep the lower jaw separate, so that a complete 

 examination of the specimen can be made at any 

 time. The lower jaw of the badger of course 

 cannot be separated from the skull without break- 

 ing the characteristic enfolding processes of the 

 upper attachment. 



It is often desirable for purposes of study to 

 obtain a disarticulated skull, and this is only 

 possible in the case of juvenile subjects whose 

 bones have not grown together. The skulls of half- 

 grown puppies, etc., will come to pieces bone by 

 bone during the process of maceration without 

 much manipulation ; but in the case of the human 

 skull, except when very young, the dovetailing of 

 the sutures will hold the whole tightly together, 

 and it is impossible to effect disarticulation from 

 without. This, however, may be effected by filling 

 the skull with hard peas and immersing it in water, 

 which will swell the peas and slowly burst the 

 skull from within. 



In the case of birds, of course, the horny beaks 

 and claws do not form part of the true bone ; but, 

 as the former are usually very characteristic, it is 

 as well to preserve them with the specimen, which 

 is easily done, as they slip off readily during the 

 process of maceration. 



The fresher the specimen, the cleaner and whiter 

 will be the bones. Specimens that have been 

 allowed to get hard and dry are more difficult to 

 bleach in proportion to their dryness. No skull, 

 however hard and dry, need be despaired of ; but 

 in such a case the simmering process gives the 

 best results. The same remark applies to speci- 

 mens that have been preserved in methylated 

 spirit, which toughens the flesh and brain beyond 

 the reach of maceration. 



It should be noted that all good specimens must 

 be kept under glass, even in the cabinet, as dust 

 combines with the trifle of grease that is always 

 present in the bone, and a skull once allowed to 

 get thus discoloured is impossible to restore to its 

 former white perfection. 



68 Wolverhampton Road, Stafford. 



Saturating Wood with Creosote. — About 

 75 lb. of creosote are required for the impregna- 

 tion of an ordinary railway sleeper. Attempts 

 have been made to reduce this quantity by dis- 

 solving the creosote in a suitable liquid, but, owing 

 to the evaporation of the solvent, have not proved 

 economical. A more successful attempt at dilution 

 is that recently described by F. Seidenschnur in 

 the Zeit. angeman. Chem. In this process the 

 creosote is formed into an emulsion with a rosin 

 soap, and water added until the required propor- 

 tion, say 15 per cent., of creosote is obtained. The 

 sleepers are steamed under pressure, then ex- 

 hausted under reduced pressure, and finally charged 

 with the creosote emulsion imder a pressure of 

 7 atmospheres. — C. A. Mitchell. 



