July 6, 1SS8.] 



SCIENTIFIC NEWS. 



*3 



give it a semi-fluid consistency. The result was good, as 

 on all my trees, after being thus dressed, not a bud was 

 damaged, and the blossom appeared in a normal manner. 

 This composition has also the advantage of destroying 

 the predatory insects which hibernate under the bark, 

 and of preventing the spotting of the fruits by moulds and 

 other fungi. The same mixture, with a little more sul- 

 phate of copper, has been employed against another 

 enemy. All horticulturists know the decided taste of 

 slugs and snails for nectarines (we may say for wall-fruit 

 in general). In spite of hunting for them in the early 

 morning, I had almost given up the hope of a crop, but 

 now I have coated the walls, the stems, and branches of 

 the trees with this composition, I have secured a full crop 

 of sound nectarines." (We give this receipt on the 

 responsibility of La Nature, but we consider it likely to 

 prove both safe and effective. — Editor, Scientific News.) 



An Anomalous Movement of Swallows. — The steamer 

 Abd-el-Kadcr, which set out about the end'of May from 

 Marseilles, bound for Algiers, when at the distance of 

 twenty-eight miles from land fell in with a large flight of 

 swallows going southwards. They alighted upon all 

 parts of the vessel, where they spent the night. At 

 seven the next morning, when off the Balearic Islands, 

 they left the steamer and all took flight in the direction oi 

 Algiers. A migration of swallows southwards at this 

 season of the year has never before been witnessed. 

 — (Cosmos) . 



The Ravages of Silpha Opaca. — This well-known 

 carrion-feeding beetle has recently taken to prey on 

 vegetable matter, and is indulging in the very pardonable 

 freak of destroying the sugar-beet. Conjointly with this 

 change in its diet it has begun to increase in a manner 

 previously unknown. This prooceeding excites great 

 wrath among the growers of betose, who are combating 

 the enemy with sulphuret of carbon. 



The " Centreing" of the Human Eye. — Some years 

 back Professor von Helmholtz showed that, optically 

 speaking, the human eye was not a perfect instrument. 

 M. Tscherning (Comptes Rendus), who has re-examined 

 the subject, finds that the adjustment of the eye is never 

 exactly centred, but the deviation is generally incon- 

 siderable. In most eyes the three centres are situate in 

 the same vertical plane, but the centre of the cornea is 

 below the axis of the crystalline lens. In other eyes the 

 centre of the cornea lies in the same vertical plane as the 

 axis of the crystalline lens. 



Observation on the Arrival of the Swallows at 

 the Park of Baleine, in LAllier. — M. G de 

 Rocquigny-Adanson gives in del et Terre a table of the 

 return of the swallows, from which it appears that the 

 extreme dates over a term of forty-one years are from 

 March 19th to April nth. Half the returns took 

 place between March 30th and April 3rd, the mean date 

 being April 1st. The solitary, unusual date of March 

 19th, occurred after the severe winter 1879-1880. 



Bird Murder. — As we learn, both from private 

 sources and from contemporaries, the massacre both of 

 hoopoes and of sand-grouse still continues. The possible 

 penalties under the Wild Birds' Protection Act are 

 ridiculously small. 



POISONS IN THE WORKSHOP. 



Yy'E admit very generally that it is the duty, or at any 

 rate the good policy, of the community to defend 

 its members as far as possible from causes of disease or 

 death. But we do not yet see that agencies, which sud- 

 denly and swiftly strike down a man who might have 

 previously been in robust health are, after all, less for- 

 midable than such as gradually undermine his vitality 

 and enable him to leave behind an enfeebled posterity. 

 We have yet to learn that the so-called "diseases of 

 debility," phthisis, scrofula, albuminuria, affections of the 

 brain and the heart, are as truly preventible as the 

 various types of pestilence. 



Among the causes of gradual decay and debility, we 

 have at present to deal merely with the poisonous pro- 

 ducts employed in the arts and manufactures. We are 

 too apt to connect the notion of poison exclusively with 

 a sharp, sudden illness, ending in death, a post-mortem 

 examination, and a coroner's inquest. But in the vast 

 majority of instances there is no sudden death ; the life 

 of the victim is not so much shortened as rendered 

 more or less useless and enjoyable. His strength fades 

 away, he undergoes often extreme suffering without 

 knowing the cause, and his death is' finally attributed to 

 some ordinary disease. 



The number of poisons which enter into our in- 

 dustrial operations is great and increasing. We will 

 accordingly take a glance at some of the most important, 

 and consider how their evil action is to be avoided or 

 overcome. 



One of the most formidable, if its effects are viewed 

 in connection with its trifling quantity, is mercury. The 

 men engaged in mining for this valuable metal, and in 

 separating it from the ore (generally cinnabar) often 

 suffer severely. Among the ordinary effects are loose- 

 ness and even entire loss of the teeth, and often formal 

 salivation. Where it is constantly absorbed into the 

 body in smaller proportions tremblings of the limbs, 

 neuralgia, or other nervous symptoms are commonly 

 observed. It is important to note that in proportion as 

 the metallurgy of mercury has been improved by pre- 

 venting the escape of the metal in the form of vapour, 

 the health of the workmen has been greatly improved. 



But much mischief is occasioned by mercury in the 

 various arts in which it is employed. Probably the 

 largest quantity is consumed in the so-called " amalga- 

 mation process," for separating gold and silver from 

 their ores. In this process vapours of mercury are con- 

 stantly given off, though not in striking quantity, and the 

 men employed cannot entirely help coming in contact 

 with the poisonous metal. The improvement devised 

 by Mr. W. Crookes, F.R.S., i.e., the use of an amalgam 

 of mercury and sodium instead of pure mercury, has 

 effected an improvement in this process from a sanitary 

 point of view, since the quantity of mercury needed is 

 reduced, and the time during which it has to be worked 

 up with the ore is shortened. 



The so-called silvering of mirrors is another extensive 

 use of mercury, and is very detrimental to the health 01 

 those employed, the more so as the operation is not per- 

 formed, like the amalgamation of gold and silver ores, in 

 the open air, or in rough sheds readily traversed by the 

 wind. The operation need not be here described in 

 detail, but it consists substantially in applying to the 

 glass, whilst in a horizontal position, sheets of smooth 

 clean tinfoil, upon which a sufficient quantity of mercury 

 is spread very evenly. This process requires careful 



