1854.] 



BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 



109 



The solution of gelatin is prepared by digesting ten grm. of dry ge- 

 latin (containing about eighteen or nineteen per cent, of water) in 

 water for twelve hours, and then applying heat until the solution is 

 complete. The volume is then made up to one litre. 



For the purpose of determining the centigrade value of the gelatin 

 solution, 0-2 grm. of pure gallo-tannic acid dried at 212" F. is dis- 

 solved in 100 or 120 grm. of water, and the gelatin solution added 

 from a graduated burette until the precipitation is complete. Filtra- 

 tion is generally necessary towards the end of the operation, or as a 

 substitute the following plan may be adopted : — A narrow open glass 

 tube is covered at one end with some tolerably thick linen bound tight 

 by cord ; on immersing this covered end into the liquid, and sucking 

 out the air by the mouth at the other end, a portion is rendered clear 

 by passing through the linen, and may be poured into a tube, and 

 tested with gelatin. 



The author found that the 0-2 grm. of pure dry tanno-gallic acid re- 

 quired from 32-5 cub. cent, of the gelatin solution for perfect precipi- 

 tation ; when the solution is some days old, a larger quantity is neces- 

 sary, 35, 38, or even 40 cub. cent. It is therefore necessary in all 

 cases, when the gelatin solution has been kept any time, to determine 

 its centigrade value by means of gallo-tannic acid immediately before 

 making any experiments with it. 



If it is required to estimate the value of oak or other barks for tan- 

 ning, they are first dried in a warm room, powdered finely, digested in 

 quantities of 10 grms. with warm water, and exhausted by means of a 

 displacement apparatus constructed of a tube two feet long, one inch 

 wide, and di-awn out at the lower end, which is loosely stopped with 

 cotton wool. Some substances may be introduced dry into this appa- 

 ratus, and exhausted by the warm or cold water. The extraction may 

 likewise be facilitated by the pressure of a column of water applied by 

 fitting a narrow glass tube with a cork into the upper end. 



In most cases, the extraction is completed in one or two days. 

 When the operation is properly conducted, the quantity of liquid ex- 

 tract amounts to half a pound or a pound. It is then treated with 

 gelatin solution so long as a precipitate is produced. A few drops of 

 dilute hydrochloric acid facilitate the separation of the coagulum. 



The quantity to be taken for an experiment of substances rich in 

 tannin, such as galls, is about 0'5 or I'O grm. A simple calculation 

 gives the per. centage of tannin. 



The author states that he has adopted this method in repeated ex- 

 aminations of tanning materials dui-ing the last ten years ; he has 

 found the results tolerably constant, and nothwithstandingits apparent 

 imperfection, more trustworthy than any other yet known. 



He estimates the relative value of several substances of this kind 

 as follows : — 



Pine bark contains from 5 to 7 percent, tannin. 



Old oak bark " 9 " " 



Best oak bark " 19 to 21 " " 



Gall nuts " 30 to S3 " " 



Aleppo galls " GO to GO " " 



Chinese galls " 70 " " 



These data at least admit of comparison with each other, and indi- 

 cate with tolerably certainty the respective value of these substances 

 to the tanner. This method of valuation is indeed based upon the as- 

 sumption that the same kind of tannin exists in all these substances. 

 It is however, extremely probable that this is not the case ; but at the 

 same time it may fairly be assumed that if different kinds of tannin 

 combine under similar conditions with different quantities of gelatin, 

 they will also combine with animal skins in the same relative propor- 

 tions. If, therefore, this method does not imlicato the absolute per- 

 centage of tannin, it still gives the per-centnge value of the substances 

 examined, and it is precisely this which the tanner requires. 



It is another question whether gelatin solution prcciptates all the 

 Bubstances of the tanning material which combine with the skin, and 

 it therefore remains to be determined by experience whether such a 

 method of valuation is sufficient for the purpose of the tanner. — I'oly- 

 technischcs Central Blatl, 1853, thronyh Journal of Induatnj Progrcus. 



TTveuty-fourtli Slectiii;; or tlic Biitisli Associatiou for tl>e 

 Aclvaiiccnicut of Science* 



LIVERPOOL, SEPTEMBER, ISo-t. 



On the Anthropoid Apes ; by PnOF. Owen. 



The Lecturer defined the known species of those large tail-less Apes, 

 which form the highest gi-oup of their order (Qaudrumana), and conse- 

 quently make the nearest approach to man ; he determined the true 

 zoological characters of the known orangs and chimpanzees, as mani- 

 fested by adult specimens ; pointed out the relative proximity of the 

 orangs and chimpanzees to the human species ; and indicated the 

 leading distinctions that separate the most anthropoid of those apes 

 from man. The Professor then entered upon the subject of the varie- 

 ties of the human species, and defined the degree in which the races 

 differed from each other in colour, stature, and modifications of the 

 skeleton. He entered upon a disquisition of the causes of these 

 varieties, and proceeded to examine how far any of the known causes 

 which modify specific characters could have operated so as to produce 

 in the chimpanzees or orangs a nearer approach to the human character 

 than they actually present. He pointed out some characters of tko 

 skeleton of the ape, e. g. the great superorbital ridge in the Gorilla 

 Ape, which could not have been produced by the habitual action of 

 muscles, or by any other known influence that, operating upon succes- 

 sive generations, produces change in the forms and proportions of 

 bones. The equable length of the human teeth, the concomitant 

 absence of any interval in the dental series, and of any sexual difference 

 in the development of particular teeth, were affirmed to be primitive 

 and unalterable specific pecularities of man. "Teeth," the Professor 

 proceeded to state, " at least such as consist of the ordinary dentine 

 of mammals, are not organized so as to be influenced in their growth 

 by the action of neighbouring muscles ; pressure upon their bony 

 sockets may affect the direction of their growth after they are pro- 

 truded, but not the specific proportions and forms of the crowns of 

 teeth of limited and determined growth. The crown of the great can- 

 ine tooth of the male Troglodytes gorilla began to be calcified when its 

 diet was precisely the same in the female, when both sexes derived 

 their sustenance from the mothers' smilk. Its growth preceded and was 

 almost completed before the sexual development had advanced so as to 

 establish those differences of habits, of force, of muscular exercise 

 which afterwards characterize the two sexes. The whole crown of the 

 great canine is, in fact, calcified before it cuts the gums or displaces 

 its small deciduous predecessor ; the weapon is prepared prior to the 

 development of the forces by which it is to bo wielded ; it is therefore 

 a structure foreordained, a predetermined character of the chimpanzee, 

 by which it is made physically superior to man ; and one can as little 

 conceive its development to be a result of external stimulus, or as being 

 influenced by the muscular actions, as the development of the stomach, 

 the testes, or the ovaria." The difference in the time of disappearance 

 of the suture separating the premaxillarj' from the maxillary bone, 

 was not explicable on any of the known causes afi'ecting such character. 

 There was not, according to the Lecturer, any other character than 

 those founded upon the developments of bone for the attachment of 

 muscles, which was known to be subject to change through the opera- 

 tion of external causes ; nine-tenths, therefore, of the diflerences, 

 especially those very striking ones manifested by the pelvis and pelvic 

 extremities, which Pro. Owen had cited in his ' Memoirs on the Orangs 

 and Chimpanzees,' published in the Zoological Transactions, as distin- 

 guishing the great chimpanzee from the human species, must stand in 

 contravention of the hypothesis of transmutation and progressive dc- 

 velopement, untU the supporters of that hypothesis arc enabled to 

 adduce the facts and cases which demonstrate the conditions of the 

 modifications of such characters. There was the same kind of diffi- 

 culty in accounting for the distinctivccharactersof the diflcrent species 

 of the orangs and the chimpanzees, as for those more marked distinc- 

 tions, that remove both kinds of apes from man. And with regard to 

 the number of the known species, Prof. Owen remarked, it is not 

 without interest to observe, that as the generic forms of tlia Quadru- 

 mana approach the Binianous order, they are represented by fewer 

 species. The gibbous (Ilylobates) scarcely number more than half- 

 a-dozen species ; the orangs (Pithecus) have but two species, or at 

 most three ; the chimpanzees (Troglodytes) arc represented by two 

 species. The unity of the human species is demonstrated by the 

 constancy of those ostcological and dental characters to which the 



