Tag Archives: Stage 12

Nudging into Blackmans Bay on Stage 12 of my walk along the Derwent River

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At 3pm I turned left onto Roslyn Ave having walked up from Boronia Beach. Within 10 minutes I could see Blackmans Bay Beach.

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Five minutes later I turned left at Blowhole Road in search of a Blowhole. The road was narrow with no pathway and limited edges on which to walk.  Wattle trees were blooming and I passed an apple orchard laden with red globes. Flowering gums are spectacular at the moment.

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I reached the Blowhole sign, which indicated the entrance to a small park on a hill at the northern end of Blackmans Bay Beach, at 3.22 pm.

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The weather wasn’t gusty and so the water ebbed and flowed rhythmically but undramatically beneath a rock bridge. There was no blowing of water through the gap.

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I continued down hill.

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I reached beach level at 3.34pm and proceeded to walk on the path beside Ocean Esplanade. Inset into the pavement were handmade tiles and mosaics presumably made by community effort.  These were similar to those impressed into the footpath in parts of Kingston.

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A little way along the Esplanade public toilets and a kid’s playground provided useful amenities.

I decided to stop, look, listen and smell. Looking over the Derwent River to the South Arm peninsula and around about me watching people enjoying the beach and surrounds, listening to the seagulls calling, and smelling the salty air kept me seated for 10 minutes. I had walked two thirds of the way along Blackmans Bay Beach and it seemed a reasonable place to stop for Stage 12.  So I headed for  a bus stop.  I found one by turning into Hazell St and then into Wells Parade.  As I arrived at the stop, a Metro bus came over the hill in the distance.  Wonderful timing.  It was 4pm. The experiences of the day had been rich. I enjoyed the bus trip back into Hobart via the main Kingston shopping centre, and then the southern outlet highway. The view when we came to the top of the final hill is majestic (please ignore the dirty bus windows in the photos below).

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Some of Hobart and the eastern shore suburbs are laid out below with the blue Derwent River flowing between. Always stunning. After half an hour on the bus I arrived in Hobart city, then headed off for my Bellerive bus and was home before 5pm.  All together a brilliant day.  Stage 12 was complete!  Because of personal commitments and what I have seen in the weather forecast, I do not expect to walk Stage 13 until next week.

Alum – what is it?

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On my next walk along the Derwent River – Stage 12, I will start by walking 3-4 kilometres along the top of the Alum Cliffs from Hinsby Beach to Kingston. I have seen the cliffs from Hinsby Beach on Stage 11, and they look like ‘normal’ cliffs.

But what is Alum? 

According to http://chemistry.about.com/od/moleculescompounds/f/What-Is-Alum.htm, “Alum is any of the compounds with the empirical formula AB(SO4)2·12H2O” and if I tell you Alum is a specific compound of hydrated potassium aluminium sulfate with the formula KAl(SO 4)₂·12H 2O, your brow may wrinkle.  Are you still in the dark?  Worse – it seems there are a number of alum varieties including:

  • Potassium alum is also known as potash alum or tawas. It is aluminium potassium sulfate. This is the type of alum that you find in the grocery store for pickling and in baking powder. It is also used in leather tanning, as a flocculant in water purification, as an ingredient in aftershave and as a treatment to fireproof textiles.
  • Soda alum, with the formula NaAl(SO4)212H2O, is used in baking powder and as an acidulent in food.
  • Ammonium alum has the formula NH4Al(SO4)212H2O and is used for many of the same purposes as potassium alum and soda alum. Ammonium alum finds applications in tanning, dyeing textiles (acts as a mordant and helps to lock in colours), making textiles flame retardant, in the manufacture of porcelain cements and vegetable glues, in water purification and in some deodorants.
  • Chrome alum or chromium alum has the formula KCr(SO4)212H2O. This deep violet compound is used in tanning and can be added to other alum to grow lavender or purple crystals.
  • Selenate alums occur when selenium takes the place of sulphur, so that instead of a sulfate you get a selenate, (SeO42-). The selenium-containing alums are strong oxidizing agents, so they can be used as antiseptics, among other uses.

Other uses of Alum

Alum has several household and industrial uses.

  • purification of drinking water as a chemical flocculant
  • in styptic pencil to stop bleeding from minor cuts
  • adjuvant in vaccines (chemical that enhances immune response)
  • deodorant “rock”
  • pickling agent to help keep pickles crisp
  • flame retardant
  • the acidic component of some types of baking powder
  • an ingredient in some homemade and commercial modelling clay
  • an ingredient in some depilatory (hair removal) waxes
  • skin whitener
  • ingredient in some brands of toothpaste

Considering this list, and in this day and age of developers raping resources, I am surprised our Alum Cliffs are still standing.

The more I learn the more I am overwhelmed by options.  I wonder what the story is of our Alum Cliffs between Hinsby Beach and Kingston. More research is required.