Crooked Mick

"I just have a feeling that wheel-driven is about the most resistant method there is, and other (less efficient but workable) methods should be available." Actually that's right. I once had a Raleigh cycle with a "Dyno-hub" which contained a power source and 3-speed epicyclic gears, this seemed to give less drag when on than a dynamo driven by the side of the tyre. The type that engage the rear wheel just behind the front sprocket I have no experience of, but I have heard that they can give trouble in the wet. Voltage was a nominal 6 I think. These things are now rare I believe. Miller cycles of the USA made something similar. Crooked Mick.

Looked into this a few years ago. You will need a generator/alternator that can be driven by a wheel. You will feel resistance as the power has to come from somewhere and that is you pushing. If the source produces alternating current, to charge a battery the AC must be turned to DC by a rectifier using diodes. These are available as rectifier packs. A capacitor across the output will smooth it out a little. Then a zener diode can cut out harmful peaks in the output from riding fast downhill. Your battery will have to be a rechargeable type. For the tail lamp a series of say four red LEDs with another four as a brake indicator - maybe. While white LED headlamps are sold for bicycles, the more conventional incandescent type may still be better even though they use more current for the same light. Frankly I think it is a waste of effort. Blinking or steady red rear lamps using a few LEDs are available from chain stores for a few dollars and a pair of penlight cells lasts for many hours of operation. I have a four penlight cell headlight with a two-intensity setting which uses an incandescent bulb and the cells have a few hours life. It might be worth your while though to check the bicycle stores or the net for this sort of system. I have seen systems with all sorts of batteries from a lead-acid to strings of nicads. Crooked Mick

Does anyone know any exact information about signal lamp oil as used by railroads up to the 1940s or a bit later? It appears to have been less flammable and more viscous than kerosene. I have this information - Density 35 degrees Baume or 0.848 sg, flash point (don't know whether open or closed cup) 280F, fire point 315F and pour point 30F. Is there a modern product that has similar properties? Crooked Mick

I first stumbled across this maybe 6 years ago while reading a copy of "Nexus" magazine for a laugh. "Nexus" makes "Fortean Times" look like real science. I don't know who originated the idea but it has been promoted by "Sir" Laurence Gardner. "Sir" Laurence has reputedly been knighted by a pretender to the throne of Scotland, who claims James II of England and perhaps Bonnie Price Charlie as an ancestor. "Sir" Laurence is also full of information on the Knights Templar, the Holy Grail bloodline and so forth. I do not recall the exact details of this article now but it did manage to contradict itself on about the same page about the "discovery" of "white high spin gold" in a well preserved Egyptian temple in the Sinai. Said temple has subsequently been lost to knowledge. Yeah, right, even archaeologists had sextants, compasses and chronometers 100 years ago. http://www.nexusmagazine.com/ http://www.graal.co.uk/ http://www.graal.co.uk/whitepowdergold.html Crooked Mick of the Speewah

"I notice that the element Carbon has a density of 2.267, while diamond (which is Carbon) has a density of about 3.5" More than likely what you have there is the density of graphite compared to the density of diamond. Both are pure carbon. In graphite the atoms arrange themselves in hexagons very like honeycombs. Because of the geometry of electronic orbitals in this arrangement the honeycomb sheets are flat, and one sheet of honeycombs stacks on top of another. However the sheets do not come really close to each other because the electrons circulating freely about the sheets tend to repel each other. In this form carbon will conduct electricity quite easily and since the sheets slide over each other the material can be used as a lubricant. Graphite is a low density, low pressure form. In diamond, the arrangement is different. Each carbon atom is arranged at the corners of a tetrahedron and is tightly bound to it's neighbours by four strong chemical bonds. This is caused by a different arrangement of the electronic orbitals which point toward the corners of a tetrahedron. Because of the tight bonding there are more atoms per cubic whatever of space and the density is higher. Also because of the tight chemical bonding, diamond is a poor conductor of electricity. Diamond is a high density, high pressure form of carbon and forms in high pressure environments such as deep in hot rocks. Several pure elements can exist in different arrangements called allotropes. Carbon, tin, phosphorus, sulphur are just some of those that can. Crooked Mick of the Speewah

You need a solvent that is selective as YT2095 suggests, I'd suggest ethanol or propanol to begin with, or possibly one of the lower ketones, acetone or methyl ethyl ketone which should dissolve the sucrose and leave MOST of the pot. chloride behind. Someone somewhere has probably tabulated the solubility of each in ethanol or acetone, but I'd guess that pot. chloride is probably slightly slightly soluble in ethanol and acetone. So the separation will not be perfect, but as a first pass with cheap readily available stuff it might not be bad. Supercritical carbon dioxide might also do it but that does not look cheap. Crooked Mick of the Speewah

If you are looking for a relatively slow generation of gas it might be worth experimenting with calcium carbonate (limestone) mixed with vinegar (dilute acetic acid) or citric acid solutions. Both vinegar and citric acid can be obtained in food grade quality, cheaply and are safe for contact with most of the human exterior except the eyes. Calcium carbonate is cheap, virtually harmless and may be sold as garden lime or dolomite when magnesium carbonate is also present. The magnesium carbonate is also non-toxic. The rate of generation of carbon dioxide gas will depend on the size range of the calcium carbonate/ dolomite, the temperature and the concentration of the acid solutions. The finer the calcium carbonate/ dolomite, the quicker the reaction. A range of sizes might give you a quick generation of some gas from the fines with a more sustained generation from the larger particles. Some basic experiments are needed here with sieves, a set of scales to weigh things, something to measure volumes and a stopwatch. While carbon dioxide is toxic, it I believe that 5% in ordinary air is the lower limit of toxicity. While it is usually said to be odourless, it is also said to have a slight musty odour. If you are intending to generate just a few litres (say a gallon or two) from a handful of materials then the danger is very low even in a closed room of ordinary size and would be about the same as opening several cans of soft drinks in the same room. Crooked Mick of the Speewah

I'm hoping this does not come across as woo-woo. I'm well aware of the dangers of spon. com. in coal and some other materials having worked in the coal industry. Couple of years ago I glanced out the window to see a neighbour's "pencil pine" or "Roman pine" tree on fire on one side, the side away from the street as it happened. The flames had only just broken out and there was nobody about. By the time I got out of the front door the neighbour was dragging a garden hose toward the tree. As I recall the weather was cool rather than hot. While mulch can show spon. com, there was no mulch about the area, the tree grew straight out of a well trimmed lawn. I decided that a butt flicked from a passing car might have been the cause but the other day on another site someone mentioned seeing a tree alight for no immediately apparent cause and another person came in with a remark about conifers. The pencil pine is of course a conifer. In these trees the upthrust branches tend to retain fallen leaves in thick lumps but whether these could retain enough heat is doubtful. The Oxford University Press in their Notes and Queries internet pages has a 19th century article on spon. com in trees but it is a pay per view site. Does anyone know anything reliable about this?

Greetings, Terraformers. There is no hope of increasing the gravitational field of Mars with any foreseeable technology. However there is the hope of increasing atmospheric density and or quantity. This might mean an approach on several concurrent and maybe even conflicting levels. First there is the old idea of steering a few asteroids into a collision course. Now I'll dismiss right away the idea of a few multi-billion tonne bodies. However a few hundred lumps of water ice in the ten thousand to million tonne range are a possibility. The difficulty is that the orbital velocities of these bodies, being further out than Mars is slower, so they would have to be accelerated to get into the inner solar system, which is energy intensive. Nuclear powered robot spacecraft that use the water ice as a propellant are the idea here, the voyage in to Mars might take decades though. Once in the vicinity, the ices are aerobraked rather than directly slammed into the Martian surface, thus at least partially avoiding Cretaceous - Tertiary boundary type events. In fact the bulk of the material does not actually have to strike the ground and could just head off out of the ecliptic plane. As the atmosphere thickens, the larger the lumps might be. Such collisions will add heat to the atmosphere, though this might not be all that significant. Another at least superficially sensible proposal is to coat some proportion of the polar caps with carbon so as to reduce albedo. The carbon could be locally made from the atmospheric CO2 or could merely be coal dust sent from Earth, at least in an early stage. This would trap more solar heat on the planet, with greater sublimation of the CO2 and water ice already there into gas. A thicker atmosphere with more H2O and CO2 implies a higher temperature and unless my chemistry is way off, a higher soil temperature could lead to outgassing of gases adsorbed by soil minerals. So an even thicker atmosphere develops. I like the idea of cyanobacteria fitted out with suicide genes. This sort of thing is increasingly possible and there is no reason to dismiss the idea of breeding such groobilies in Mars jars right here on Earth. We could start with microorganisms that seem to thrive in Antarctic regions, though that might not be where the ultimate success stories come from. Mars might eventually have low elevation areas with a climate resembling that of high altitude Peru. Just a few words on a Martian base. There is no good reason to try to send everything required on a single space craft. Launch a few Saturn V equivalents loaded with a ground habitat, supplies etc. When that stuff has landed satisfactorily, then send your manned craft. They arrive to find shipping containers full of cans of beans and wheelbarrows ready for use. The habitat can have some radiation shielding, more could be obtained by placing sandbags filled locally on the roof. Crooked Mick of the Speewah Says - Always dry between your toes.

Back in 1997 exterior seating was built outside a building in Canberra, Australia. It was built onto a hip high concrete block wall which ran within a few degrees of North-South. The seat was on the eastern side and a line of trees sheltered it from the western sun in the afternoons. The seat was hardwood timber, perhaps 45mm thick, 120mm wide, really solid stuff, supported by steel brackets underneath. The brackets were fixed to the timber by heavy screws, from below, these did not reach the top surface of the timber. The brackets were just visible from a distance if you looked hard enough. From close up they were not visible except through the gaps between the timber, perhaps 10 mm wide. The timber was varnished, probably polyurethane. After a few year's weathering, the varnish began to flake and erode. I noticed that the greatest erosion was in the areas between the brackets and the least erosion was immediately above the brackets. Why did the varnish show least erosion above the brackets? The seating has since been demolished as the building is being extended, or I might have been able to supply a photo. This has baffled be for some time. One of life's minor mysteries? Or is there a real explanation familiar to folk in the paint business? Crooked Mick

Try an expanding grout. I believe these contain aluminium powder, the cement alkali releases hydrogen. No smoking! Can these be mixed with ordinary (Portland) cement? I don't know. Possibly. This is a question for a building supplier. Expanding grout has been used on pre-stressed, post-tensioned concrete bridges.

One of the standard methods is to titrate with borax, sodium tetraborate decahydrate. This is a "secondary" standard and a sufficiently accurate solution for most purposes can be made by dissolving a weighed amount in water after GENTLE drying. However I do not know whether the presence of a lot of Al2(SO4)3 would affect the end point a great deal. Indicator was, if memory serves methyl red in presence of methylene blue. Colour change was purple -green, more or less. See standard methods for determination of sulphur in coal by the high temperature tube furnace method. Can't be more specific, it's 18 years since I've done this.