June i, 1887,] 



ttiE TKOPiCAL AGJ^lCULTURlS'f, 



853f' 



PURIFICATION OF DRINKING WATER. 



EDWIN J. HOWE, M. D. 



The average healthy adult mau takes into his sys- 

 tem four and a half pounds of water daily, and with 

 it too often a dangerous quantity of foreign matter 

 and disease-producing germs. In very many homes 

 during the summer months, water that otherwise 

 would nauseate the drinker, is made cold by ice, and 

 then is hastily swallowed, the coldness masking its 

 offensiveness. Unfortunately for the health of the 

 consumer, the addition of ice does not render the 

 impurities in water innocuous, but often adds to it 

 its own contribution of disease-germs. Those who 

 have studied the subject are aware that impure drink- 

 ing water is the cause of many of the most common 

 diseases. No subject then is of greater importance 

 to the public than how to purify our drinking water. 

 Water, if drawn through lead and tin pipes, often 

 becomes, contaminated with these metals to a dangerous 

 extent. Where water remains in a lead pipe for 

 twenty-four hours, and is then drawn off and drank, 

 there is always danger of lead poisoning. It is always 

 safer to let the water run for several minutes be- 

 fore using any for drinking purposes. Boiling the 

 water destroys some germs, but does not remove im- 

 purities in solution. Analyses of water from city wells 

 have frequently shown it to be so impure as to be 

 utterly unfit for drinking purposes, and dangerous to 

 health. The use of rain water caught in cisterns, 

 with suitable precautions, will obviate most dangers 

 from the present supplies of many cities, but un- 

 fortunately, few persons can take these " suitable 

 precautions." A clean roof to collect the rain, clean 

 pipe to transport, and ;i clean, well ventilated cistern 

 to receive it, are essential. Water stored in a close 

 cistern soon becomes unfit for use. Many waters that 

 appear clear are full of impurities, and dangerous to 

 health. Dr. Ezra Hunt says : There are many waters 

 used for drinking, which, if kept a few days in a long 

 glass tube, balf full and corked, will, on opening, emit 

 much odour from the change in the suspended or 

 dissolved ingredients they contain." The large major- 

 ity of people in cities must depend for water on the 

 public supply, hence it is of the utmost importance 

 to the public health that the purest water attainable 

 be secured ; this, unfortunately, is often very im- 

 pure. The only safe-guard to the consumer is in 

 giving his personal attention to the filtration of the 

 water used in his household. Water slowly perco- 

 lated through crushed vegetable charcoal will escape 

 from it not only cleansed of particles held in suspen- 

 sion, but also of organic and other matter. The 

 cheepnesa of charcoal is such that is obtainable by 

 all classes, and when soiled, a fresh quantity can be 

 substituted at trifling cost. The most effective filtra- 

 tion is obtained by placing crushed charcoal in an 

 earthen vessel, so arranged as to compel the slow 

 passage of the water through it, as all efforts at 

 rapid filtration have proved inefficient. Only wooden 

 spigots should be used in drawing of the water. A 

 reservoir for the filtered water with a separate ice 

 chamber, will permit the water to be sufficiently 

 chilled and keep all ice impurities out. Such a con» 

 trivance requires but very little room, is easily 

 cleaned^ the coal renewed, and is efficient in free- 

 ing water from impurities. — Indian Gardener. 



AMOUNT OF FAT IN FISH GUANO, 



BY JOHN HUGHKS, ¥. C. S., V. I. C. 



Of late years finely ground dried fish, ccmmonly 

 known under the name of fish guano, has been ex- 

 tensively used as a separate manure, with very 

 Satisfactory results. On naturally poor sandy soils, 

 as well as on the light chalk soils of Kent and 

 Susses, it makes a capital mabure for potatoes, es- 

 pecially when used in conjuuctiCn with superphosphate 

 and kainit salts. That fish should form a valuable ferti- 

 liser is nob at all singular; indeed, its agricultural 

 value has long been recognised by the farmers of 

 the sea coast in all countries, but the peculiarly 

 pffeo6iv§ pbaracter of decompo^iog gsb bae bitberto 



prevented its extensive use, and it is only of recent 

 years, since attention has been directed to the 

 removal of tlie greater portion of the natural 

 moisture and the subsequent grinding into a fine 

 powder that the article has become of commercial 

 value. 



The name of fish guano seems appropriate, inas- 

 much as there can be little doubt that fish was the 

 original source of Peruvian guano, the latter consist- 

 ing in fact of the dung of sea-fowl, whose only food 

 wjis fish. In the one case we have the natural dried 

 fish, and in the other we have the same material 

 which, under a process of slow decomposition in vast 

 heaps under the influence of a hot rainless climate, 

 has been converted into the stroug-smelling ammo- 

 niacal guano of Peru and Chili now, alas ! becoming 

 only too scarce. 



It is well, however, to bear in mind that there are 

 differences in the agricultural value of the new guano 

 as there was and still exists in the cargoes of the old, 

 and that not only do the proportions of phosphates and 

 ammonia vary considerably in quantity, but that the 

 rapidity with which these constituents can be rendered 

 available as plant food is also likely to vary according 

 to the special character of the prepared fish, and more 

 particularl.y in relation to its freedom from fatty or oily 

 matter. Fat, as we all know, is a great preservative o 

 animal and vegetable substauc s, and therefore any 

 large quantity of fat or oil is prejudicial to the natural 

 decomposition of fish manure when applied to the soil, 

 and it will be desirable to encourage the manufacturer 

 to press out or extract by chemical means as much oil 

 as possible. 



It must be remembered that fat has no agriculturcl 

 value in a manurial sense, and that its presence in close 

 association with an organic material rich in nitrogen 

 and phosphates tends very materially to retard the 

 natural process of conversion of these ingredients into 

 plant food. 



With a view of showing clearly to what extent the 

 proportion of oil varies in different samples of fish guano, 

 some dozen specimens repre.senting the average quali- 

 ties prepared by different firms were carefully tested 

 for the amount of oil or fat contained, and the 

 results, with the relative amounts of nitrogen and phos- 

 phate of lime present in each, are set forth in the 

 following table : — 



Equal to Phosphate 

 Sample. Oil. Nitrogen Ammonia. of Lime. 

 1 ... 580 ... 7-26 ... 8-81 ... 15-98 

 :> ... 603 ... 7-68 ... 9-82 ... 19-54 



3 ... 6-96 ... 890 ... 10-80 ... 16-94 



4 ... 7-30 ... 6-94 ... 8-43 ... 16-46 



5 ... 8-33 ... 8-71 ... 10-57 ... 19-54 



6 ... 8-90 ... 8-54 ... 10-37 .-. 18'88 



7 ... 8-36 ... 8'68 ... 10o4 ... 15-94 



8 ... 7-96 ... 8-71 ... 10-57 ... 30-63 



9 ... 893 ... 8-69 ... 10-55 ... 18-99 



10 ... 10-10 ... 8'66 ... 10'51 ... 17-79 



11 ... 1-2-56 ... 8-48 ... 10-30 ... 15-06 



12 ... 17'06 ... 9-45 ... 11-47 ... 914 



It will be seen that the oil varies from 5-80 in one 

 sample to 17-06 in another, and that the specimens 

 which show from 6 to 9 per cent, of oil are those which 

 are the richest in nitrogen and phosphates combined. 



In order, therefore, to keep down the proportion of 

 oil in commercial sanjplesj it is suggested that the 

 amount of this constituent should be stated in the 

 analysis in addition to the other itemSj and if this be 

 asked for by buyers, the manufacturer will, no deubt, 

 soon find means to reduce the fat in the best make of 

 fish guano. — Analytical Laboratory, 79, Mark Lane, E.O. 

 — Agricultural Gazette. 



CULTIVATION OF CAOUTCHOUC-YIELUINQ 

 PLANTS. 



BY TMOMAS T. T. liRnCE WARRENj 



Looking at the increasing commercial importance 

 of india-rubber, and the few fresh sources of supply 

 which have been added to augment our stock of this 

 subi-tance, we are forced to admit that the activity of 

 our experts have not been marked with that succos^i 

 wbifb a roauufftcturpr can wish for, 



