March 1, 1866.] 



SCIENCE-GOSSIP. 



53 



relates to the detection of blood-stains. "For- 

 tunately, the various modifications of the colour- 

 ing - matter of blood yield such well-marked and 

 characteristic spectra, that there are few sub- 

 jects to which the spectrum microscope can be 

 applied with greater advantage than the detection 

 of blood-stains. I have already, in my paper in the 

 Quarterly Journal of Science (April, 1S65, II. 205), 

 entered at so great length into this question, that I 

 need not say much about it on the present occasion. 

 The form of apparatus I have described enables us, 

 however, to examine the objects in a different man- 

 ner : surface illumination may be used, provided a 

 sufficiently bright light be thrown on the object by 

 means of a parabolic reflector or bull's-eye con- 

 denser. A speck of blood on white paper shows 

 the spectrum very well, provided it be fresh, and the 

 colour be neither too dark nor too light, and the 

 thickness of the colouring matter neither too great 

 nor too little. A mere atom, invisible to the naked 

 eye, which would not weigh above the millionth of 

 a grain, is then sufficient to show the characteristic 

 absorption bands. They are, however, far better 

 seen in solution. About -^ of a grain of liquid 

 blood, in a cell of -jo of an inch in diameter, and 

 -2 inch long, gives a spectrum as well marked as could 

 be desired. In exhibiting the instrument to a num- 

 ber of persons at a meeting, I have found that no 

 object is more convenient, or excites more attention, 

 than one in which a number of cells are fixed in a 

 line, side by side, containing a solution of various 

 red-colouring matters. In one I mount blood, which 

 gives two well-marked absorption bands in the green; 

 in another magenta, which gives only one distinct 

 band in the green; and in another I place the juice 

 of some red-coloured fruit, which shows no well- 

 defined absorption band. Keeping a larger cell con- 

 taining blood on the stage attached to the eye-piece, 

 these three objects can be passed one after another 

 in front of the object-glass, and the total difference 

 between the spectrum of blood and that of either 

 fruit-juice or magenta, and the perfect identity of 

 the spectra when both arc blood, can be seen at a 

 glance. By holding coloured glasses, which cut off 

 the red, but allow the green rays to pass, we can 

 readily show how the presence of any foreign colour- 

 ing matter, whicli entirely alters the general colour, 

 might not in any degree disguise the characteristic 

 part of the spectrum ; and by changing the cell held 

 on the eye-piece for a tube containing an ammoniacal 

 solution of cochineal, it is easy to show that, though 

 it yields a spectrum with two absorption bands, 

 more like those due to blood thanl have seen in any 

 other substance, they differ so much in relation, size, 

 and position, that there is no chance of their being 

 confounded when compared together side by side." 

 Any of our readers specially interested in the 

 subject are recommended to peruse the article from 

 which the above extracts have been made. 



A BOUQUET OF GRASSES. 



" The green grass on the streamlet's brim, 

 A blade of grass it is to him, 

 And it is nothing more." 



EEW people are aware of the beauty to be found 

 in many members of the Grass family. Even 

 our agricultural grasses are very ornamental when 

 properly dried and arranged. I believe about a 

 hundred and sixteen species of grasses are found in 

 Great Britain, aud from this number I shall select a 

 few of the most desirable, leaving what are called 

 the "Ornamental grasses " for another gossip. 



I would first state that in order to preserve 

 grasses for winter bouquets it is requisite to cut 

 them when they are just coming into flower, before 

 any seeds are formed, when the pollen first becomes 

 visible, and dry them by sticking the stems into 

 boxes of sand. 



The Meadow Bucetum or Fescue, which has 

 puzzled botanists a good deal in determining its 

 character, presents a very graceful, wavy appearance. 

 It is generally found in meadow ground, and flowers 

 about the middle of June. The rough-stalk Meadow- 

 grass, better known, perhaps, as the famous 

 Orchistore grass, from being found of extraordinary 

 size in a meadow near Salisbury, called Orchistore, 

 is also very pretty. Its flowers may be looked for 

 about the second week in June in well-irrigated 

 land. TheFiorin grass, which some farmers anathe- 

 matize as a weed, is another elegant addition to the 

 dried bouquet ; and the crested Dog's-tail, known in 

 Ireland by the name of Trahneen, looks remarkably 

 well ; its flowering stems are very wiry, and often 

 used in the manufacture of imitation Leghorn bon- 

 nets. The sweet Vernal grass, the only British 

 grass that is odoriferous, so like in scent to that 

 charming little plant the wood-ruff, blossoms early 

 in May, and is to be met with in thickets and on poor 

 up-land pastures. Then we have the perennial Bye- 

 grass, which village girls are so fond of trying their 

 fortunes with, to the measxu - e of "Tinker, tailor, 

 soldier, sailor, &c.;" and the rough Cock's- foot grass, 

 found so common in Norfolk. The Fox-tail, whicli 

 only occurs in deep, rich, moist, and sheltered ground; 

 together with the Cat's-tail, found on clayey soil ; 

 and last, though not least, the Sea-lime grass, which, 

 I believe, is rather rare except on chalky soil. It 

 grows nearly two feet high, is of a sort of greyish- 

 blue colour, and decidedly worthy of being classed 

 among our most ornamental grasses. Ferris have 

 been the rage for some time, even the most common 

 kinds of British ; and mosses, too, have their ad- 

 mirers : why should we not have a grosser]/, or mix 

 some of our native grasses witli our ferns? I 

 believe the effect would be better than when grown 

 in a formal way by themselves. 



H. E. Watnet. 



