1G3 



KNOWLEDGE 



[Dkc. 23, 1881. 



EngliBh writiTH dpcll " I'jinilk'IapuliKlon ? " Hutli in GcTmnn niui 

 French thii worJ is iihvays gpolt " PnmlloU'pidudon " and paialliW- 

 pipi'dii (c iinji. Dictioiinniro do I'Acndi^mio nnd Littru's Diclion- 

 iiairo), and ono «! tlm prcati'st iiuthoritios in clndsicnl phil<di<fry 

 usoarcg mo tliut the o of " pamllolos," boinR on un-ussontial tcrnii- 

 nution, muni yield to tho initial o of "cpi." — G. L. 



[118] -How TO Make Cotton WATEurnooF. — Will any of tho 

 readers of Knowledge bo pood euougli to indicate a proccsB by 

 means of which raw cotton wool, juat as the plant furnishes it, can 

 bo mado iinporvious to water, without changing tho libi'e or colour 

 of tho cotton ? — CorroNi.vN. 



[110] — Electbo Plating. — By mistake, nearly six ounces of a 

 cyanide of ooppor eolutiun have boon thrown in two gallons nearly 

 of a double cyanide of silver solution. Would any of yonr readers 

 be kind enough to tell ino liow to purify my silver solution ?— W. 

 Van Ev.-i. 



[120] Transit of Venvs, Dec, 1882.— As the above transit will 

 take place in December next year, I should vei-y much like to know 

 how the calculations are made in order to a.scortain tho sun's dis- 

 tance from the earth. I have a slight knowledge of how the work 

 is performed, but should like to understand the sy.stcm properly. — 

 Hesketm. [Will, before long, give a simide account of the matter. 

 —Ed.] 



[121] — Latitude and Longitude. — I am an.vions to be able to 

 determine the latitude and longitude in a practical manner. Will 

 you kindly, at your earliest convenience, give me the necessary 

 instructions in Knowledge ? — IlESKETn. [The best advice we can 

 give " Hcsketh" is to obtain Loomis's excellent treatise on " Prac- 

 tical Astronomy," in which the best methods of determining longi- 

 tude and latitude are clearly and fully explained. — Ed.] 



[122]— Blood Analysis — Is there any method by which the 

 amount of the albumen, or, at least, of tlie saline constituents of 

 blood, can be estimated quantitatively, in cases where only a small 

 quantity can bo obtained, say 5 c.c. ? Can tho spectroscope be 

 applied to quantitative analyses in such cases ? — iiifia. 



[123] — Fermentation in Beer. — Will you kindly allow mo to 

 ask if any of the readers of K.vowledge will explain to mo the 

 process of fermentation in beer ? — In Re. 



[124]— The Coffee Leaf.— Have you heard anything lately of 

 any experiments made in this country to introduce the coffee leaf 

 among us ? My reason for asking is that I think our labourers 

 would derive a great benefit from its use, if it could be introduced. — 

 F. C. S. 



[125] — Indigo. — Is it possible to prepare indigo on a large scale 

 artificially, and at the same time profitably ? I have heard rumours 

 that there is a manufactory in France for doing so ; but have looked 

 through, as they have arrived, my society's journals to sec if I 

 could find an account of the experiment, if any has been made, but 

 it has been without success. If you could enlighten mo on the 

 above you would oblige.— F. C. S. 



[126] — Flora, and Plants, and Insects of the ChanneI' 

 Islands. — Why are the plants of the Channel Islands included in 

 the British flora, while the insects are usually considered French ? — 

 B.J. 



[127] — Double Refr^ution. — I should bo very glad indeed of 

 information upon tho following points : — When a spot of light 

 is viewed through a piece of Iceland spar, twe spots are seen, 

 as a consequence of the double refraction of tho ci-ystal ; and if 

 I understand rightly, one of them consists of vibrations, say, in 

 vortical, and the other of vibrations in horizontal planes. Now, 

 if we look at these through a second piece of spar, we see four spots 

 of light, each of tho former pair being doubled or " resolved." 

 What I want to know is tho moaning of " resolved." If ono of the 

 first pair consists of vertical vibrations, -where do tho horizontal 

 ones come from to form its second imago ? and if the other consists 

 of horizontal vibrations, how do we come by the second imago ? 

 Each pair behaves, when tho spars arc revolved, in the same manner 

 as the first pair would if seen through a Nicol prism.— Polar. [It 

 depends how the second piece is held. If it is held with its prin- 

 cipal section parallel to the other's, only two images are seen, one 

 by ordinary, the other by extraordinary refraction. The same if the 

 principal sections are 1K0° from each other, unless tho crystals are 

 of equal thickness, when there is but one image. If the principal 

 sections are at right angles, only two images arc seen, which are 

 (I) the ordinary image after extraordinary, and (2) tho extraordinary 

 after ordinarj- refraction. In intermediate positions, four images 

 are seen, because neither the ordinary nor tho oxtraordiaary refracted 

 rays would have, in order to pass through, to turn through quite a 

 right angle, which, and which alone, would involve total extinction. 

 —Ed.] 



[128] — The Eve as one of the Senses. — I wish to give an 

 essay, or a reading on this subject at a Working Man's Mutual 

 Improvomont Society. I should be extremely obliged with any 



information that would enable mc to get a cheap pamphlet, or any- 

 thing that will help me to prepare such an essay on " The Eye, one 

 of tho Gateways of Wisdom."- T. T. 



[129] — Me1)I< AL Botany. — Will you kindly tell me thronifh 

 your valuable paper tho iinmo of the beat inn.ifivil l,.,f..i.v w-iii 

 dingrama.— Henky Hawkes-Spink. 



iUpIifS to funics. 



[20] — Orrery. — In the Museum of Philosophical Apparatus, at 

 University College, Gower-street, London, wag, and probably now 

 is, the Orrery made by the celebrated self-taught astronomer, Jamea 

 Ferguson. — W. H. Hardy. 



[06] — Venus Casting Shadow. — In India 1 have repeatedly seen 

 Venus at least two hours before sunset. In 1819 or 1850, while 

 driving on a moonless night, wo perceived on the road a distinct, 

 though faiot, shadow of a clump of trees, of two large poles, Ac., 

 cast by Venus. This was not far from Delhi, in a very dry, clear 

 atmosjiherc. — Cogito. 



[72] — A.STIQUITV OF TQE PYEAillDS.— Notwithstanding Sir John 

 Lubbock's statement, there is no trustworthy evidence that the 

 Pyramids "are at least 6,000 years old." The Great Pyramid of 

 Geezeh is generally admitted to be not only the greatest, but also 

 the oldest, and astronomical considerations based upon the position 

 of its entrance-passage — which constitute evidence of a much more 

 reliable character than that of ancient Egv-ptian ti'aditions — indi- 

 cate that its age does not exceed 1,051 years. — J. Baxendell. 



[Mr. Baxendell fails to notice that the direction of the entrance- 

 passage fulfilled the condition of pointing towards Alpha Draconis 

 at its sub-polar'passage, at two epochs during the last 25,000 years — 

 one that which he mentions, the other some 6,*->00 years ago. More- 

 over, what no one seems to have noticed yet, tho ascending passage, 

 which 4,051 years ago would have been directed towards no im- 

 portant star, would have been directed towards the most interesting 

 orb in the whole star-sphere — namely. Alpha Centauri — at its 

 southern culmination, at the earlier epoch. It has been supposed 

 by pei-sons unacquainted with astronomy that the Pleiades occupied 

 the corresponding position 4,V!00 years ago. But this is not the 

 case. The relation indicated by Prof. Smyth was only a symbolical, 

 not an observational one. — Ed.] 



[83] — Chemical Queries. — In reply to "Theion" (a), there are 

 sevei-al allotropic modifications of sulphur, as the following table 

 shows (Valentin's '" Introduction to Inorganic Chemistry, p. 53) : — 



1. Octahedral. 



2. Prismatic. 



3. Plastic. 



1-98 

 1-95 



4. Amorphous. 195 



( Arc 



in; Po 

 115 



on verted inl 

 ■ oetaliedral 

 motUfication. 



) Ini 

 ) In; 



Si.lul.ili(y in C8.». 

 Soluble. 

 Insoluble before 



transformation. 

 Insoluble. 



soluble. 



Another modification insoluble in CS. is contained in flowers of sul- 

 phur, and is of a light yellow colour (Roscoe and Schorlcmmer's 

 " Treatise on Chemistry," vol. i. p. 292). If " Theion " will carefully 

 read Roscoe's " Lessons" again, ho will find that the plastic modili- 

 cation, while (ciiai ions, is insoluble in CSj. When the tenacious form 

 has become hard and brittle, a portion will dissolve in the CS., and 

 leave a dark-brown powder (" Treatise," vol. i. p. 292). Miller 

 and some other chemists call this a grey amorphous powder. This 

 latter modification corresponds to No. 4 in the above table, (h.) 

 The word -nitrous should bo nitric. It is stated correctly in the 

 " Treatise on Chemistrj-," vol. i. p. 42G. — C. W. D. 



[84]— Ancient Man. — Mr. Homer's researches were published 

 in the " Philos. Trans.," 1855 and 1S5S, and reviewed in the 

 Qiiarterhi Review in 1859. His argument for an extreme antiquity 

 of Egyptian civilisation from finding fragments of pottery at con- 

 siderable depths in tho alluvial soil is now considered iusuflicient. 

 Sir C. Lvell says, ''it is not worth while to notice such absui-dities." 

 Other pieces of Greek origin have been exhumed at greater depths, 

 and 1 believe the Greek honeysuckle ornament was found on some 

 of Mr. Horner's. Stephenson turned uj) a brick of Mehemet Ali's, 

 even at a lower level. Stone implemeuts from Egypt have fre- 

 quently been exhibited at the Anthropological Institute, by Sir J. 

 Lubbock in 1874, Capt. Burton in 1875, and General Pitt Rivers in 

 1881, but with regard to many of these, there is great doubt as to 

 whether they are hand-fashioned, and even those which are, do not 

 prove the existence of a stone age in the Nile Valley, for Prof. 

 Owen 'says, " Chert, chipped to an edge, or flint flakes struck off 

 by percussion, being the onlained materials for circumcision and for 

 tho abdominal cut in mummifying, tho finding of flint knives in 

 Egypt requii-es evidence of the date when they were used, or of 

 previous manufacture, before they can apply to the question of a 



