What’s happening: Ice forming on roses in the back drip line; most of the blackberry lily seeds have disappeared.
What’s still green: Juniper and other evergreens, some Apache plume, yuccas, some Japanese honeysuckle, pyracantha, red hot poker, grape hyacinth, Jupiter’s beard, large-leaved soapwort, sea pink, hollyhock, oriental poppy, blue flax, yellow and pink evening primroses, vinca, gypsum phacelia, tumble mustard, snakeweed, dandelion, anthemis, coreopsis, perky Sue, Shasta daisy, black-eyed Susan, strap leaf aster leaves; June, pampas, brome, cheat and base of needle grasses; rose stems and young chamisa branches.
What’s grey, blue-grey or grey-green: Piñon, four-winged salt bush, buddleia, pinks, snow-in-summer, loco weed, yellow alyssum, stick leaf, western stickseed, winterfat, golden hairy aster leaves.
What’s red/turning red: Privet, cholla, prickly pear, small-leaved soapwort, beards tongues, coral bells leaves.
What’s yellow/turning yellow: Arborvitae; globe and weeping willow branches.
What’s blooming inside: Aptenia, asparagus fern.
Animal sightings: The night after the snow fell a mouse was on my kitchen counter after I went to bed looking for food.
Weather: First snow Thursday; returned as fog this morning; 9:45 hours of daylight today.
Weekly update: Tuesday morning I could smell wood smoke when I walked out to my car. Across the river I could see dark smoke rising from someone burning. I’m not a good enough woodsmen to recognize the burning wood, but I can often tell when some one’s firing Russian thistle.
Most weeds produce a grey-white smoke. When Russian thistles ignite, which they do with a great whoosh, the smoke turns dark, with a touch of fatty yellow. The fumes are so acrid they attack my throat and make it difficult to breathe. My hair reeks until it’s washed.
When it grows in saline environments, Salsola tragus sequesters the salt it absorbs in vacuole sacs in its leaves. When it burns, the sodium is converted to carbonate of soda. If the soil is more normal, the alkaline ashes instead contain a carbonate of potash, itself a form of potassium.
Na2CO3, better known as washing soda, is used to bleach linen, for making soap and as the flux is manufacturing glass. The origins of glass making are lost in prehistory: Roman tradition gave credit to the Phoenicians, while the earliest evidence of a fully realized industry has been recovered from iron age Tell Amarna in Egypt dated around 1350 bc. The latter used soda from Lake Natron, while people living along the modern Syrian coast are the ones credited with discovering how to extract the compound from seaside plants.
The Romans mass produced glass, especially in Sidon in modern Lebanon where someone introduced glass blowing during the time of Augustus (31 bc–14 ad). The Romans later took glass making to Valencia and Murcia in Spain, areas conquered by the Umayyads of Syria in 714.
By the time Renaissance industrial demand increased, farmers around Cartagena in Murcia and Alacant on the Valencian coast planted barrilla, which was burned in pits covered with earth where the sodium carbonate had to be broken from the walls with hammers.
The most likely plants used by the Spanish were Salsola soda, Salsola kali, and Salsola sativa, now classed as Halogeton sativus.
The idea of burning the annual chenopods spread north to France where Salsola kali and our Russian thistle, there called soude épineuse or thorny soda, were used to produce blanquette around Montpellier, between Frontignan and Aiguemortes. The plants weren’t seeded like they were in Spain, but were burned in heaps in trenches for 8 or 9 days in late summer. The soda formed an "adhesive, almost vitreous mass" that remained red hot. When the blanquette cooled, it hardened and turned black. Water was then used to extract it from the residue.
The best always came from the Levant and was used to produce the clear cristallo glass made for Venice at Murano. The soda from Spain produced a bluish glass, while that from France was greenish.
The demand for organic sources for glass making declined after Nicolas Leblanc patented a process to produce sodium carbonate from salt, sulfuric acid, limestone and coal in 1791. In 1861, Ernest Solvay substituted ammonia for the acid. Mass production and a taste for large windows followed.
However, the need to burn weeds persisted. People here don’t burn Russian thistles because of some ties to a coastal Spain they never knew, nor have then reinvented something in the face of recurring circumstances. Instead, burning’s a relic from the time before the Phoenicians when the transformative power of fire was culturally important for both pragmatic and philosophical reasons.
Glass is a pyramid of fires. Natural glass is formed when fire heats the underlying sand to produce obsidian. The soda that lowers the melting temperature comes from burning weeds. The lime that stabilizes the soda-silica compound often comes from burning shells or limestone. Man-made glass forms when quartz granules are burned with soda and lime.
Science has demystified fire by calling it heat. Urban life and, more recently, anti-burning ordinances have done much to eliminate fire from our inherited tool kit, but it persists here in the Española valley in the varieties of smoke that greet one in the morning.
Burning is still a primordial ritual that inspires fear when thistles ignite, even if the curiosity to rake through the ashes has been lost.
Notes: Glass color doesn’t come from the soda, but from mineral impurities or additives in the mix.
Chaptal, Jean-Antoine-Claude. "Blanquette" in Chemistry Applied to Arts and Manufactures, volume 2, 1807.
Guibourt, Nicolas Jean Baptiste Gaston. Work near Cherbourg published in Journal de Chimie Medicale in March 1840 and reported as "Analysis of the Ashes of the Salsola tragus" in The London and Edinburgh Philosophical Magazine and Journal of Science, July 1840.
Kauffman, C. H. "Barilla" in The Dictionary of Merchandise, and Nomenclature in All Languages, 1805.
Nesbitt, Alexander and Henry James Powell. "History of Glass Manufacture" in Encyclopedia Britannica, 1911.
Pliny the Elder (Gaius Plinius Secundus). Naturalis Historia, translated by John F. Healy as Natural History: A Selection, 1991.
Photograph: Russian thistle just after it ignited in the gathering mist before the snow, 16 December 2010; winterfat in back is not burning; all the flame and smoke are from a single plant.